Counter suggestion, the CK mini in the other suggestion is invalid and there are other usable sales. Partial credit to whatever you decide your name is.

Sold for Kill-Watt El Jefe (29 keys) + 15 keys = 44 keys

http://backpack.tf/profiles/76561198064844173?time=1434092400 (Before)

http://backpack.tf/profiles/76561198064844173?time=1434351600 (After)

Sold for Hellfire Sola Topi (~32 keys, see http://backpack.tf/vote/id/5589fa88dea9e9710c8b465b )

http://www.tf2outpost.com/trade/26199046

Sales from other suggestion (but edited to fit my format)

Sold for Collector's Professional killstreak beggars bazooka, outlier

http://backpack.tf/profiles/76561198116821062?time=1434870000

http://backpack.tf/profiles/76561198116821062?time=1435021990

Quicksold for lvl 1 max head(22 keys) and 3 keys = 25 keys, outlier

http://www.tf2outpost.com/trade/26149565

http://backpack.tf/profiles/76561198077789424?time=1433574000

http://backpack.tf/profiles/76561198077789424?time=1433746800

Offered on (and sold for) a duped Orbiting Fire Cold Killer (~38, year outdated and no mini possible aside from my 36 key B/O) + 1 bud (~3 keys)

http://www.tf2outpost.com/trade/26239697#latest

http://backpack.tf/profiles/76561198097976497?time=1434697200

http://backpack.tf/profiles/76561198097976497?time=1434783600

------- CK mini:

------- Quickbought for 22 keys

------- http://www.tf2outpost.com/trade/26016542

------- http://backpack.tf/profiles/76561198001759277?time=1432450800

------- http://backpack.tf/profiles/76561198001759277?time=1432882800