New sale:

https://backpack.tf/profiles/76561198067282796#!/compare/1529884800/1530057600

https://backpack.tf/profiles/76561198080179568#!/compare/1529971200/1530057600

Sold with sweets for a Subatomic Universal Translator

https://gyazo.com/54b9ced64898d610b411cc0bd7e21a2c

Current seller at 17 keys for half a month on this. Also 99.99% sure that the B/O was lower than 20 keys on this.

As for the new sale, 4 keys were added along a Subatomic Universal Translator.

Sales on the Universal Translator:

https://backpack.tf/profiles/76561198342161127#!/compare/1529798400/1529884800

https://backpack.tf/profiles/76561198205939253#!/compare/1529798400/1529884800

Went to a buyer so likely qbuy price.

https://backpack.tf/profiles/76561198027378787#!/compare/1529625600/1529712000

https://backpack.tf/profiles/76561198205939253#!/compare/1529625600/1529712000

Sold for 15 keys.

https://backpack.tf/profiles/76561198166314775#!/compare/1529712000/1529798400

https://backpack.tf/profiles/76561198091179527#!/compare/1529712000/1529798400

Sold for 16 keys.

https://backpack.tf/profiles/76561198166314775#!/compare/1529625600/1529712000

https://backpack.tf/profiles/76561198044563807#!/compare/1529625600/1529712000

Bulk.

https://backpack.tf/profiles/76561198044563807#!/compare/1529193600/1529280000

https://backpack.tf/profiles/76561198155219465#!/compare/1529193600/1529366400

Probably 16

https://backpack.tf/profiles/76561198155219465#!/compare/1529020800/1529107200

https://backpack.tf/profiles/76561198209640976#!/compare/1529020800/1529107200

~18

https://backpack.tf/profiles/76561198179529599#!/compare/1528934400/1529020800

https://backpack.tf/profiles/76561198209640976#!/compare/1528934400/1529020800

16 keys

https://backpack.tf/profiles/76561198128682296#!/compare/1528934400/1529020800

https://backpack.tf/profiles/76561198146640595#!/compare/1528934400/1529020800

Sold for 19 keys.

https://backpack.tf/profiles/76561198298781776#!/compare/1528588800/1528761600

https://backpack.tf/profiles/76561198444332876#!/compare/1528675200/1528761600

Not using.

https://backpack.tf/profiles/76561198314695066#!/compare/1527897600/1527984000

https://backpack.tf/profiles/76561198444332876#!/compare/1527897600/1527984000

Sold for 18 keys.

https://backpack.tf/profiles/76561198089976309#!/compare/1527811200/1527897600

https://backpack.tf/profiles/76561198314695066#!/compare/1527811200/1527897600

Sold for 17 keys.

https://backpack.tf/profiles/76561198002757046#!/compare/1527724800/1527811200

https://backpack.tf/profiles/76561198089976309#!/compare/1527724800/1527811200

Sold for 17 keys.

https://backpack.tf/profiles/76561198080193062#!/compare/1529020800/1529107200

https://backpack.tf/profiles/76561198080179568#!/compare/1528934400/1529020800

Untrace. SCM.

https://backpack.tf/profiles/76561198002757046#!/compare/1526947200/1527033600

https://backpack.tf/profiles/76561198106824379#!/compare/1526947200/1527033600

Sold for 18 keys.

https://backpack.tf/profiles/76561198084367252#!/compare/1525564800/1525651200

Sold for 17 keys.

https://backpack.tf/profiles/76561198136023847#!/compare/1526169600/1526515200

Went to a scammer.

Sales in the last 2 months on marketplace:

https://marketplace.tf/items/30658;5;u93

Sold for $50 ( / $1,96 ) = 26 keys

Sold for $43.25 ( / $1,96 ) = 22 keys

Sold for $43 ( / $1,97 ) = 22 keys

Sold for $43.59 ( / $1,94 ) = 23 keys

Sold for $45 ( / $1,93 ) = 23 keys

Sold for $50 ( / $1,95 ) = 26 keys

https://backpack.tf/profiles/76561198003724587#!/compare/1530057600/1530144000

https://backpack.tf/profiles/76561198352608887#!/compare/1530144000/1530230400

Sold for 17 keys.

https://backpack.tf/profiles/76561198344933095#!/compare/1531087200/1531173600

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Sold for ~20 keys.

https://backpack.tf/profiles/76561198304138933#!/compare/1529445600/1529532000

https://backpack.tf/profiles/76561198147914281#!/compare/1529452800/1529539200

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Just a few ref seems to match, though it's likely it sold for the pure amount listed.

https://backpack.tf/profiles/76561198823690736#!/compare/1528329600/1528416000

https://backpack.tf/profiles/76561198304138933#!/compare/1528408800/1528495200

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Sold for 19 keys.

https://backpack.tf/profiles/76561198396322888#!/compare/1530741600/1530828000

https://backpack.tf/profiles/76561198048492330#!/compare/1530316800/1530403200

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Bought for 15 keys.

https://backpack.tf/profiles/76561198304138933#!/compare/1529272800/1529359200

https://backpack.tf/profiles/76561198049884052#!/compare/1529193600/1529280000

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Bought for ~16 keys.

https://backpack.tf/profiles/76561198304138933#!/compare/1528149600/1528236000

https://backpack.tf/profiles/76561198245624680#!/compare/1528070400/1528156800

https://gyazo.com/f3e0f77e3d01a804d0e124558f54d1e6

Bought for ~16 keys.

https://backpack.tf/profiles/76561198141472321#!/compare/1528416000/1528588800

https://backpack.tf/profiles/76561198075781327#!/compare/1528588800/1528675200

http://www.tf2outpost.com/user/76561198141472321 - no B/O

Sold for a Purple Confetti Thirst Blood (17) + 2 keys + small sweets = 19 keys.

https://backpack.tf/profiles/76561198092345997#!/compare/1528416000/1528588800

https://backpack.tf/profiles/76561198214364347#!/compare/1528502400/1528588800

http://www.tf2outpost.com/user/76561198092345997 - no B/O

Probably better used there. Would probably be 20ish.

https://backpack.tf/profiles/76561198415479324#!/compare/1528156800/1528243200

https://backpack.tf/profiles/76561198141054773#!/compare/1528156800/1528243200

Bulk.

https://backpack.tf/profiles/76561198024867201#!/compare/1531008000/1531094400

https://backpack.tf/profiles/76561198830056399#!/compare/1531008000/1531094400

Quickbought.

https://backpack.tf/item/6532735859 -> more scrap.tf sales in that history.

https://backpack.tf/profiles/76561198093926010#!/compare/1531094400/1531180800

https://backpack.tf/profiles/76561198262354524#!/compare/1531008000/1531180800

Bulk.

https://backpack.tf/profiles/76561198101322839#!/compare/1530489600/1530576000

https://backpack.tf/profiles/76561198262354524#!/compare/1530403200/1530489600

Better used there.

https://backpack.tf/profiles/76561198000693929#!/compare/1529884800/1529971200

https://backpack.tf/profiles/76561198144739518#!/compare/1529884800/1529971200

Bulk.

https://backpack.tf/profiles/76561198179529599#!/compare/1528329600/1528416000

https://backpack.tf/profiles/76561197960323012#!/compare/1528329600/1528416000

Better used on the taunt.

https://backpack.tf/profiles/76561198225902076#!/compare/1528070400/1528156800

https://backpack.tf/profiles/76561197960323012#!/compare/1528156800/1528243200

Sold for 18 keys.

https://backpack.tf/profiles/76561198137326742#!/compare/1528070400/1528156800

https://backpack.tf/profiles/76561198225902076#!/compare/1528070400/1528156800

Sold for 17 keys.

https://backpack.tf/profiles/76561198155558267#!/compare/1525996800/1526169600

https://backpack.tf/profiles/76561198179707937#!/compare/1526083200/1526169600

http://www.tf2outpost.com/user/76561198179707937 - no B/O

Sold for a Magnetic Hat Protector Universal Translator (19) + 1 key = 20 keys.

https://backpack.tf/profiles/76561198258362014#!/compare/1527984000/1528156800

https://backpack.tf/profiles/76561198054758757#!/compare/1527897600/1527984000

Sold for 19 keys.

https://backpack.tf/profiles/76561198058912060#!/compare/1528329600/1528502400

Sold for 18 keys.

https://backpack.tf/profiles/76561198024867201#!/compare/1527724800/1527811200

https://backpack.tf/profiles/76561198090339904#!/compare/1527724800/1527811200

Sold for 18 keys.

https://backpack.tf/profiles/76561198098480978#!/compare/1531094400/1531267200

https://backpack.tf/profiles/76561198179707937#!/compare/1531094400/1531180800

Bulk.

https://backpack.tf/profiles/76561198329367143#!/compare/1530662400/1531440000

https://backpack.tf/profiles/76561198098480978#!/compare/1530489600/1531008000

Untrace.

https://backpack.tf/profiles/76561198821557752#!/compare/1528416000/1528502400

https://backpack.tf/profiles/76561198823690736#!/compare/1528416000/1528502400

Better used there.

https://backpack.tf/profiles/76561198286946145#!/compare/1527638400/1528329600

https://backpack.tf/profiles/76561198305536788#!/compare/1526688000/1527638400

Untrace. Other side of the compare link doesn't even exist (yet), likely alts/friends/cash.

https://backpack.tf/profiles/76561198155320889#!/compare/1525910400/1525996800

https://backpack.tf/profiles/76561198060016607#!/compare/1525910400/1525996800

Sold for 19 keys.

https://backpack.tf/profiles/76561198080179568#!/compare/1527552000/1527638400

https://backpack.tf/profiles/76561198152788827#!/compare/1527552000/1527638400

Sold for 19 keys.

https://backpack.tf/profiles/76561198084845448#!/compare/1528243200/1528329600

https://backpack.tf/profiles/76561198054758757#!/compare/1528156800/1528243200

Sold for 18 keys.

https://backpack.tf/profiles/76561198018823501#!/compare/1526428800/1526515200

https://backpack.tf/profiles/76561198102323117#!/compare/1526428800/1526515200

Sold for a Blizzardy Storm Helmet Without a Home (11) + 4 keys.

https://backpack.tf/profiles/76561198343885717#!/compare/1529625600/1529712000

https://backpack.tf/profiles/76561198176735142#!/compare/1529539200/1529712000

Sold for 17 keys.

https://backpack.tf/profiles/76561198343885717#!/compare/1529798400/1529884800

https://backpack.tf/profiles/76561198048492330#!/compare/1529798400/1529884800

Sold for 17 keys.

https://backpack.tf/profiles/76561198053851830#!/compare/1526947200/1527120000

https://backpack.tf/profiles/76561197997040330#!/compare/1526947200/1527120000

Better used there.

So basically the sales on the Universal Translator are:

15 x2

16 x4

17 x7

18 x6

19 x6

20 x2

22 x2

23 x3

25> 2x

Current market: https://gyazo.com/11b6d860dd45a1cebf7a6974dbbe5200

15 seems a tad low so I'd make 16 keys the low end. Most of the sales at 17-20 went relatively fast, some even within a day. And only 1 of the current sellers at 20 is matured whereas there are 7 sales above 20 keys. 25> can probably be excluded. 23 keys would probably be fine as a high-end since there's still plenty of sales around that data point including sales at 25 (which are too high, but support 23 keys). So I wouldn't mind a somewhat larger range there since the sales and sellers support that.

If the Universal Translator turns out at 16-23 keys, that would make it ~20 keys. Minus the 4 keys in sweets/pure added that would make the sale 16 keys.

Your other sale is basically outdated at this point and a seller at 17 keys on the Runner's Warm-Up also counter that sale. I'd probably just go with 16 flat here.