The proof is not the best. Maybe you just should open a trade where you buy them for 1 key.

http://www.tf2outpost.com/trade/5930455

http://www.tf2outpost.com/trade/5923812

http://www.tf2outpost.com/trade/5796560

These are all on the first 3 pages of outpost not sold for a key. Downvoted

High demand, but also massive supply.

I got a pink one for a pittance back when it was semi-new, there's just too much competition from sellers.

X

every one of these I've had I was able to sell for 3 ref with a bit of a wait.