Hello and welcome to my another unusual suggestion.

Sold mine for 50 keys pure. B/O was 50 (took me only ~1-2 weeks):

http://backpack.tf/profiles/76561198176125115#!/compare/1467417600/1467504000 (Compare will show 51 keys but only 50 keys were involved in the trade and the other 1 is from a different trade.)

http://www.tf2outpost.com/trade/28275004

Sold for Death at Dusk Tavish DeGroot Experience (~38.5) + 13 Pure. Makes around ~51.5 :

http://backpack.tf/profiles/76561198053060686#!/compare/1465603200/1465862400

Rounding to ~50

Any suggestion/Updates/Proof/Counter-Proof is gladly accepted :) Thanks for your time