Using last month

Sales 1 & 2:

Sold for $19.99 and $13.89 on Marketplace.tf

https://marketplace.tf/items/1112;5;u3010

19.99/1.95 = ~10.3

13.89/1.98 = ~7.02

X = 10

X = 7

Sale 3:

Sold for 4 keys + Victory Lap (~2.5)

No outpost

Seller: https://backpack.tf/profiles/76561198370808682#!/compare/1524700800/1524873600

Buyer: https://backpack.tf/profiles/76561198268676455#!/compare/1524355200/1524873600

X = 6.5

Sale 4:

Sold for 5 keys + 16 ref

Seller: https://backpack.tf/profiles/76561198344933095#!/compare/1522886400/1522972800

Buyer: https://backpack.tf/profiles/76561198243193024#!/compare/1522540800/1522972800

Bot.tf confirms: https://i.imgur.com/1MNgB5q.png

X = 5.5

Sale 5:

Sold for 5 keys + ~15 ref

Seller: https://backpack.tf/profiles/76561198344933095#!/compare/1523577600/1523664000

Buyer: https://backpack.tf/profiles/76561198202308457#!/compare/1523577600/1523664000

Bot.tf confirms: https://i.imgur.com/1MNgB5q.png

Seller’s end shows 18 ref matching, there’s a chance that some of the ref was obtained in a separate trade that occurred pretty close to this one. Either way, it adds up to 5.5 keys.

X = 5.5

Sale 6:

Sold for 5 keys

Seller: https://backpack.tf/profiles/76561198097271466#!/compare/1524268800/1524355200

Buyer: https://backpack.tf/profiles/76561198122445210#!/compare/1524355200/1524441600

X = 5

Sale 7:

Quicksold for 5 keys

Seller: https://backpack.tf/profiles/76561198018528305#!/compare/1523145600/1523232000

Buyer: https://backpack.tf/profiles/76561198285271920#!/compare/1523145600/1523318400

X = 5

Sale 8:

Sold for 5 keys (ID’s match)

Seller: https://backpack.tf/profiles/76561198080179568#!/compare/1523577600/1523664000

Buyer: https://backpack.tf/profiles/76561198109077451#!/compare/1522972800/1524355200

X = 5

Sale 9:

Quicksold for 4 keys + 24 ref

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1523404800/1523491200

Buyer: https://backpack.tf/profiles/76561198092449612#!/compare/1523404800/1523491200

Somewhat untraceable, but bot.tf confirms: https://i.imgur.com/1MNgB5q.png

X = 5

Sale 10:

Quicksold for 4 keys + 5.33 ref

Seller: https://backpack.tf/profiles/76561198122445210#!/compare/1524441600/1524528000

Buyer: https://backpack.tf/profiles/76561198398105948#!/compare/1524441600/1524528000

X = 4

Sale 11:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198317753977#!/compare/1524614400/1524873600

Buyer: https://backpack.tf/profiles/76561198370808682#!/compare/1524700800/1524873600

X = 4

Sale 12:

Sold for Purple Confetti Head Hedge + some war paints

Seller: https://backpack.tf/profiles/76561198268676455#!/compare/1524873600/1525046400

Buyer: https://backpack.tf/profiles/76561198094832933#!/compare/1524873600/1525046400

Too high, excluding.

Sale 13:

Sold for a bunch of items

Seller: https://backpack.tf/profiles/76561198285271920#!/compare/1523404800/1523491200

Buyer: https://backpack.tf/profiles/76561198804570231#!/compare/1523404800/1523491200

Not using this sale.

Sales 14 & 15:

https://bot.tf/stats/item?def=1112&q=5&ef=Mega+Strike&craft=1&aus=0&ks=0

2 untraceable bot.tf sales at ~6 keys. Clicking on the links do not help, as these items appear to have been sold on the day they were bought, and I can’t trace the buyers, making it impossible to find the item’s histories. These sales will fit in the range anyways.

Sellers:

~5.6 keys:

https://i.imgur.com/zkMN91Z.png

https://backpack.tf/item/5394016795

~5.65 keys:

https://i.imgur.com/vRDBWZK.png

https://backpack.tf/item/2885931217

10 keys:

https://i.imgur.com/cnH2nsY.png

https://backpack.tf/item/5041045714

12 keys:

http://www.tf2outpost.com/trade/29634005

13 keys:

https://i.imgur.com/eI7ma4m.png

https://backpack.tf/item/2876702500

Sales at:

4 (2x)

5 (4x)

5.5 (2x)

6.5

7

10

10 is an outlier, excluding.

Some of the sales at 5 may have been quicksells, but they occurred far too often to be excluded.

https://i.imgur.com/UR9CNPC.png - Buyer at 4, excluding 4.

Going with 5-7.