You're going to need more proof than just 1 trade.

1.66 ref is not possible or very very hard to sell at (I know of experience) and a key is between 2.88/2 = 1.44

Have to downvote

Another "I sold for _number of keys" suggestion.

Even if one trade was remotely near enough proof, that'd make the price of this trade 1.44 or 1.55, wouldn't it?

I still have one I'm trying to sell, and if anything it seems to me like the price should be going down not up according to what people are offering.

http://www.tf2outpost.com/trade/6908507

http://www.tf2outpost.com/trade/6951606

http://www.tf2outpost.com/trade/6721044