Making a new suggestion with more proof. Price needs a refresh.

Big thanks to Foamy the Fearsome for supplying almost all the proof.

Sale 1:

My sale of the Smoking Rack for 37 Keys pure

Screen of trade http://i.imgur.com/hWYK6Ys.png

Screen of my BP with Rack http://i.imgur.com/PFHg9mv.png

Screen of my BP with Keys http://i.imgur.com/xF4rsVG.png

-> 37 Keys

Sale 2:

Sold for DP exe (~40) + NnB bonk boy (~20)

http://www.tf2outpost.com/trade/26025485 BO 40

http://backpack.tf/profiles/76561198067025442?time=1433228400 before

http://backpack.tf/profiles/76561198067025442?time=1433646118 after

Exe is outdated but the sale easily exceeds 40

-> 40 keys

Sale 3:

Sold for powersurge stainless pot (~37)

http://backpack.tf/profiles/76561198072853758?time=1432146445 before

http://backpack.tf/profiles/76561198072853758?time=1432364400 after

0.9*37 = ~34

-> 34 keys

Sale 4:

Sold + NnB lucky shot for MG engi cap

http://backpack.tf/profiles/76561198082000583?time=1430887742 before

http://backpack.tf/profiles/76561198082000583?time=1430895600 after

Sale 5:

Sold + NnB lucky shot for duped overclocked tipped lid

http://backpack.tf/profiles/76561198100305846?time=1430550000 before

http://backpack.tf/profiles/76561198100305846?time=1430703575 after

Probably an outlier, as even with the clean value of the lid this sale would be ~25 ish

Sale 6:

Sold for 32 keys

http://www.tf2outpost.com/trade/26000796

http://backpack.tf/profiles/76561198032223595?time=1432560777 before

http://backpack.tf/profiles/76561198032223595 after

-> 32 keys

Sale 7:

Sold for planets cold killer (~22) + Smoking yellow belt (~18) + 3 keys

http://www.tf2outpost.com/trade/25836135

http://backpack.tf/profiles/76561198121382675?time=1430428554 before

http://backpack.tf/profiles/76561198121382675?time=1430463600 after

http://www.tf2outpost.com/trade/25956802 Belt is just a few days outdated at 21, but has a ton of sellers below, lowest of which is at 18

0.9*(18+22) + 3 = ~39

-> 39 keys