Here comes the suggestion bombing!

Sold with ~1 Key in Sweets for a Strange Spec KS Gunslinger(~22 Keys)(21 Keys total)(N/O was 20)

http://backpack.tf/profiles/76561198164903609/#!/compare/1457337600/1457769600

http://backpack.tf/profiles/76561198120446950/#!/compare/1457769600/1457856000

http://www.tf2outpost.com/trade/27930608

Sold for Kill-a-Watt Wet Works(19 Keys) and ~6 Keys in Sweets(25 Keys total)(B/O was 20)

http://backpack.tf/profiles/76561198031371895/#!/compare/1454745600/1454832000

http://www.tf2outpost.com/trade/27688532

Sold for an Australium Flame Thrower(19 Keys) and a Bruiser's Bandana(1 Key)(20 Keys total)

http://backpack.tf/profiles/76561198019556015/#!/compare/1456473600/1456560000

Sales seem to fit, 20 Keys should be fine.

Additional Proof/Counter-Proof/Constructive Criticism/Feedback is always appreciated.