If at first you don't succeed, walk into that swamp. Also if you've succeeded. Either way: into that swamp. Nothing dangerous there. Go in.

http://www.tf2outpost.com/trade/24474310 Selling for 4.5 keys

http://www.tf2outpost.com/trade/24308286 Seemingly sold for 4 keys + 5 ref, and 5 ref was .3 of a key at the time of trade.

http://www.tf2outpost.com/trade/24441266 Seller at 4 keys, not included in the range because the trader seems to be inexperienced, it's a killstreak, and it's pretty young, but it still shows that even more people sell lower than the current range.