Just sold mine for 7 keys.

http://www.tf2outpost.com/trade/8249297#/29542145

Cheapest b/o's on the market:

http://www.tf2outpost.com/trade/8436102 b/o 6 keys

http://www.tf2outpost.com/trade/8474281 b/o 6 + 2 ref

http://www.tf2outpost.com/trade/8458402 b/o 7-8 keys

Plenty of others asking 8-10 keys for theirs.

This is the cheapest one i could find. It sold for 5 keys in less than a day:

http://www.tf2outpost.com/trade/8382730 (2 days ago)

http://backpack.tf/id/76561197980541478?time=1360137600 appears into this guy's BP the same day. So I'd call that a quicksell.

Steam Market: $14.72 which with keys at $2.27 there makes it 6.5 keys

Warehouse: 63,495 credits which you would have to trade keys in at 12,600 makes it about 5 keys. They only have 25 in stock though, which to me means it's pretty cheap. I personally ignore any warehouse data b/c I think it's bogus. Way to difficult to get credits unless you buy them with bitcoins to be true market prices. Just my $0.02

Redoing this based off the comments from my previous suggestion:

http://backpack.tf/vote/id/51158762ba2536185c000001

As always, dropping the price is super easy, but how dare I try to raise a price! :P