Technically, there's only one valid sale at 40:

Started working on a counter, but the other sales dont really check out:

Sale 1:

Sold for Blizzy yellow belt (~30) + KS aussie black box (~18) + 1 key + genuine KE

http://www.tf2outpost.com/trade/26349222 BO 40

http://backpack.tf/profiles/76561198049370335?time=1436425200 before

http://backpack.tf/profiles/76561198049370335?time=1438153200 after

Yellow belt is outdated, but is probably above the 20 it needs to be to be allowed to cap this sale at its buyout of 40 (based on offers of the ones currently on the market)

-> 40 keys

Sale 2:

Vanished:

No OP trade

http://backpack.tf/profiles/76561198167599626?time=1435647600 before

http://backpack.tf/profiles/76561198167599626?time=1435820400 after

Dunno

- The 'seller' at 36 sold it too long ago so its no longer valid

- The 'seller' at 34 has had the item listed for sale twice, but neither of the outpost trades were bumped as far as I can see. It seems to have indirectly sold for this steaming timless topper (histories dont match up, not sure what happened exactly:

http://backpack.tf/profiles/76561198054277592?time=1435302391

http://backpack.tf/profiles/76561198054277592?time=1435474800

http://backpack.tf/item/697255622

It's probably best to wait until this sells again before pricing it

[EDIT] Unless the others have recently sold (I dont have premium so I cant track the other miami slopokes)