Sale 1:

Sold with Buds (<2) for Planets Brown Bomber (21.5)

No outpost

Seller: http://backpack.tf/profiles/76561198063383864#!/compare/1483142400/1483228800

Buyer: http://backpack.tf/profiles/76561198327976824#!/compare/1483142400/1483228800

X = 20

Sale 2:

Sold for Planets Lucky Shot (18) + 1 keys + Spec. KS Scattergun (~1)

No outpost

Seller: http://backpack.tf/profiles/76561198315845408#!/compare/1483920000/1484006400

Buyer: http://backpack.tf/profiles/76561198131014883#!/compare/1483920000/1484006400

X = 20

Sale 3:

Sold for Spec. KS Aussie Grenade Launcher (15) + ~2 keys in metal/items

No outpost

Seller: http://backpack.tf/profiles/76561198157508353#!/compare/1483833600/1483920000

Buyer: http://backpack.tf/profiles/76561198096673788#!/compare/1483833600/1483920000

X = 17

Sale 4: (Dupe)

Quicksold for 16 keys

http://www.tf2outpost.com/trade/28666595 - B/O of 17

Seller: http://backpack.tf/profiles/76561198070371220#!/compare/1481932800/1482019200

Buyer: http://backpack.tf/profiles/76561198153194745#!/compare/1481932800/1482019200

X = 16

Sale 5:

Sold with ~11 keys in items for Tesla Coil Titanium Pillar of Hats (24)

Seller: http://backpack.tf/profiles/76561198182752986#!/compare/1486857600/1487116800

Buyer: http://backpack.tf/profiles/76561198287496233#!/compare/1486771200/1486857600

X = 13

This’ll be way too low here. Can be used on the Pillar when it goes outdated, which is very soon.

Sale 6:

Sold for 10 keys + ~2 keys in items

http://www.tf2outpost.com/trade/28699432 - B/O of 18

Seller: http://backpack.tf/profiles/76561198327976824#!/compare/1483574400/1483660800

Buyer: http://backpack.tf/profiles/76561198209268289#!/compare/1483488000/1483660800

X = 12

Sale 7:

Sold for Smoking Air Dog

http://www.tf2outpost.com/trade/28708350 - B/O of 19

Seller: http://backpack.tf/profiles/76561198096673788#!/compare/1483833600/1483920000

Buyer: http://backpack.tf/profiles/76561198315845408#!/compare/1483833600/1483920000

Should probably be used to update the Air Dog, hat looks rather overpriced.

Sale 8:

Sold with 2 keys + <0.5 keys in items for Cloud 9 Brim

Seller: http://backpack.tf/profiles/76561198131014883#!/compare/1484352000/1484438400

Buyer: http://backpack.tf/profiles/76561198141324089#!/compare/1484438400/1484524800

Should probably be used on the brim.

Sellers:

18 keys:

http://i.imgur.com/j195CWD.png - 8 days

http://backpack.tf/u/76561198108148076

20 keys:

http://i.imgur.com/6g0iNU8.png - 24 days

http://backpack.tf/u/76561198287496233

http://www.tf2outpost.com/trade/28794213

Buyer at 16 keys:

[u]Sales at:

12

13

16

17

20 (2x)

Sales at 16 and below are countered by the buyer at 16. Excluding 16 and below.

Going with 17-20.