I feel the current price of this item is too high. Many people selling for 4 keys. Some sell for even less. Last price update for this was a month ago.

http://www.tf2outpost.com/trade/6723733 Seller at 4 keys

http://www.tf2outpost.com/trade/6729928 Wants 3 keys 1.66 ref

http://www.tf2outpost.com/trade/6620614 someone willing to sell at 3 keys

http://www.tf2outpost.com/trade/6270725 lots of people willing to sell gold at 4 keys (oldish trade, I know.)

http://www.tf2outpost.com/trade/6697403 unsold at 5 (his launcher has many things attached)

Only 1 page of buyers and 3 pages of sellers. Not hard at all to buy for 4 keys, and probably not that hard to buy for 3-3.5 either.