Yeah I guess this'll do.

Sold for an Isotope Brain Candy Knife(Field-Tested)(45 Keys) and an Australium Bkack Box(18 Keys at the time)(63 Keys total)

https://backpack.tf/profiles/76561198061508957#!/compare/1462147200/1462233600

https://backpack.tf/profiles/76561198123100066#!/compare/1462233600/1462320000

Seller at 55 Keys: http://www.tf2outpost.com/trade/28281180 (3 Weeks unsold on classifieds)

63 is the only useable sale here, leaving the 55 seller as the low end. 55-63 Keys should be fine.

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