Copy paste from K1ng, all credits to him c:

Most likely quicksold for 31 keys (credits Torb)

https://backpack.tf/profiles/76561198140010255#!/compare/1512086400/1512172800

Smoking Kabuto (mini at 19) and 19 keys (credits Torb) ----- 38 keys

https://backpack.tf/profiles/76561198359394527#!/compare/1512172800/1512259200

Smoking Kabuto has sales at ~18 and ~20 here

https://marketplace.tf/items/152;5;u35

HG Kabuto (45) (credits Torb)

https://backpack.tf/profiles/76561198067948618#!/compare/1512691200/1512777600

Sold for an unusual RL (mini at 39) (credits Torb)

https://backpack.tf/profiles/76561198067948618#!/compare/1513209600/1513296000

The RL sold with 2 keys for a PKS Aussie Medigun (~41 keys based on classies listings)

https://backpack.tf/profiles/76561198066595010#!/compare/1513728000/1513814400

https://backpack.tf/profiles/76561198184412705#!/compare/1513728000/1513814400

Hellish Most Wanted (10.5?) + Max's Head (19.6) ----- ~30 keys, but the taunt was surely worth more at the time.

https://backpack.tf/profiles/76561198324760849#!/compare/1513555200/1513900800

https://backpack.tf/profiles/76561198274139380#!/compare/1513814400/1513900800

https://marketplace.tf/items/30614;5;u3013 ----- Sales at ~17 and ~25 keys in December. Better to ignore this sale

Not sure, probably Neutron Spartan (unpriced) + sweets based on IDs.

https://backpack.tf/profiles/76561198274139380#!/compare/1514160000/1514246400

https://backpack.tf/profiles/76561197993987295#!/compare/1514592000/1514678400

https://backpack.tf/suggestion/5a5d66e4cf6c75526c1f5676 ----- being priced at ~36.5

Sold for 29 keys?

https://backpack.tf/profiles/76561197993987295#!/compare/1514764800/1514851200

https://backpack.tf/profiles/76561198052246700#!/compare/1514764800/1514851200

http://www.tf2outpost.com/trade/29498667 ----- sold in ~2 days

Most likely quicksold for 28 keys to a buy order

https://backpack.tf/profiles/76561198179131749#!/compare/1515888000/1516060800

https://backpack.tf/profiles/76561198023051867#!/compare/1515801600/1515888000

So there are sales at 28 (qs), 29 (qs), 31 (qs?), 38, 39, 45. 38-39 should work.