Someone has to do it

Proof:

Solds:

http://backpack.tf/profiles/76561198118601370#!/compare/1468454400/1468540800 ~ sold for 2 keys + 10 ref . ~ 2.5

Sellers:

http://www.tf2outpost.com/trade/28339007 ~ 2 keys

http://www.tf2outpost.com/trade/28338925 ~ 2 keys

http://www.tf2outpost.com/trade/28338599 ~ 4 keys

http://www.tf2outpost.com/trade/28336424 ~ 2 keys + 5 ref

http://www.tf2outpost.com/trade/28326031 ~ 2.5 (2 keys 10 ref)

http://www.tf2outpost.com/trade/28336718 ~ 2 keys

http://www.tf2outpost.com/trade/28323005 ~ was offered 2 keys, and 1 key 10 ref twice.

2 keys looks good, as the sellers, and the last seller being offered 2 keys, and the sold at 2.5 (probably was a bit more hyped, but exclude the sale cause of the sellers at 2)