Sale 1:

Sold for Miami Nights Elf Esteem (13.5) + 2 keys

No outpost

Seller: https://backpack.tf/profiles/76561198143892063#!/compare/1495152000/1495238400

Buyer: https://backpack.tf/profiles/76561198150082447#!/compare/1495152000/1495238400

X = 16

Sale 2:

Sold with <0.5 keys in cosmetics for Pro. KS Blood Botkiller Sniper Rifle (9) + 5 keys

No outpost

Seller: https://backpack.tf/profiles/76561198131911699#!/compare/1492214400/1492387200

Buyer: https://backpack.tf/profiles/76561198061826706#!/compare/1492300800/1492387200

X = 14

Sale 3:

Sold for Spec. KS Aussie Black Box (13) + <0.5 keys in metal/items

http://www.tf2outpost.com/trade/29175648 - B/O of 13

Seller: https://backpack.tf/profiles/76561198067055238#!/compare/1494547200/1494633600

Buyer: https://backpack.tf/profiles/76561198324455724#!/compare/1494547200/1494633600

X = 13

Sale 4:

Sold with a key for Terror-Watt Hive Minder (13.5)

http://www.tf2outpost.com/trade/29178003 - B/O of 15.5

Seller: https://backpack.tf/profiles/76561198324455724#!/compare/1494633600/1494720000

Buyer: https://backpack.tf/profiles/76561198267189538#!/compare/1494633600/1494720000

X = 13

Sale 5:

Sold with Kazotsky (>1.5) for 12 keys

No outpost

Seller: https://backpack.tf/profiles/76561198061826706#!/compare/1492473600/1492560000

Buyer: https://backpack.tf/profiles/76561198097135729#!/compare/1492473600/1492560000

X = 10

Sale 6:

Bulk for Infernal Flames Conga

Seller: https://backpack.tf/profiles/76561198091502579#!/compare/1497312000/1497398400

Buyer: https://backpack.tf/profiles/76561198210225228#!/compare/1497312000/1497398400

Sale 7:

Something to do with the medigun

Seller: https://backpack.tf/profiles/76561198002757046#!/compare/1491177600/1491264000

Buyer: https://backpack.tf/profiles/76561198131911699#!/compare/1491091200/1491264000

Sale 8:

Bulk for Secret Coupe

Seller: https://backpack.tf/profiles/76561198271935163#!/compare/1492646400/1492732800

Buyer: https://backpack.tf/profiles/76561198232041512#!/compare/1492646400/1492732800

Sale 9:

Sold with 2 keys for Dead Presidents Company Man + cosmetic?

No outpost

Seller: https://backpack.tf/profiles/76561198076819824#!/compare/1491523200/1491609600

Buyer: https://backpack.tf/profiles/76561198078560380#!/compare/1491523200/1491609600

Hard to tell if this is correct, the items that disappear on the seller’s end probably got turned into keys/metal and were used on the company man. Probably better to not use this sale at all.

Sale 10:

Sold for Stormy Storm Virtual Reality Headset

http://www.tf2outpost.com/trade/28989140 - B/O of 15

Seller: https://backpack.tf/profiles/76561198271428863#!/compare/1494460800/1494547200

Buyer: https://backpack.tf/profiles/76561198067055238#!/compare/1494460800/1494547200

Couldn’t get a mini on the Headset, probably better to use this to update the headset instead.

Sellers:

16 keys:

http://i.imgur.com/U1QzU0m.png - 13 days

https://backpack.tf/u/76561198210225228

http://www.tf2outpost.com/trade/29228093

Sales at:

10

13 (2x)

14

16

10 looks like a low outlier, and there is a buyer at 10 keys:

http://i.imgur.com/rT4qZRe.png

Excluding 10.

Going with 13-16.