First suggestion!

Sale 1:

Sold with a S. Medi Mask (~4) and a S. Bunnyhoppers Balistics (~.5) for a Stormy Detective Noir (23).

23 - 4 = 19

Seller: https://backpack.tf/profiles/76561198172263746#!/compare/1502928000/1503014400

Buyer: https://backpack.tf/profiles/76561198050062763#!/compare/1502928000/1503014400

Sale 2:

Sold for 14 pure.

Seller: https://backpack.tf/profiles/76561197964546925#!/compare/1498435200/1498521600

Buyer: https://backpack.tf/profiles/76561198031469492#!/compare/1498521600/1498694400

Sale 3 (?): 1:1 for a Starstorm Winter Woodsman (36-39)

Seller: https://backpack.tf/profiles/76561198123630648#!/compare/1497484800/1497830400

Buyer: https://backpack.tf/profiles/76561198182752986#!/compare/1497657600/1498262400

Sale 4: untracable:

Seller: https://backpack.tf/profiles/76561198040601138#!/compare/1497571200/1497657600

Buyer: https://backpack.tf/profiles/76561198011695067#!/compare/1497484800/1497571200

Only one for sale on the comm market:

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

57.70 / 2.1 = ~27.5

14

19

27

37

14 looks like a QS and 37 is a clear outlier. Going with 19-27. Suggestions or corrections welcome!