Looks like this is in high demand, needs a boost

http://www.tf2outpost.com/trade/5052596- Guess he wasn't online, but someone added him to pay 1 key for dominations

http://www.tf2outpost.com/trade/9841421- Added for 1 key

http://www.tf2outpost.com/trade/9889715- The trade is new, but only wants 4 ref for it

http://www.tf2outpost.com/trade/9863948- Wanted 4 ref for it, accepted a 3.66 offer

http://www.tf2outpost.com/trade/9861558- Had it posted for 3 ref, probably would've been snatched up right away have it not been untradable

http://www.tf2outpost.com/trade/9680930- Had it set for 1 key, got an offer of 4.22 and accepted

http://www.tf2outpost.com/trade/9889684- My trade, sold it for 1 key with relative ease

TL;DR There are trades where it sells for a key quick, but there are some who post for less