Updating the price. Proof is below. Very difficult to sell it at the current price, people are willing to sell cheaper.

Sellers:

http://www.tf2outpost.com/trade/9570787 - 4 keys, unsold, 1 week

http://www.tf2outpost.com/trade/9509432 - 4 keys, unsold, 1 week

http://www.tf2outpost.com/trade/9593345 - 4 keys, unsold, 1 week

http://www.tf2outpost.com/trade/9585857 - 4 keys, unsold, 1 week

http://www.tf2outpost.com/trade/9616534 - 4 keys, unsold, 6 days

http://www.tf2outpost.com/trade/9671081 - 4 keys, unsold, 4 days

http://www.tf2outpost.com/trade/9651356 - 4 keys, unsold, 4 days

http://www.tf2outpost.com/trade/9690219 - 4 keys, unsold, 3 days

http://www.tf2outpost.com/trade/9719255 - 4 keys, unsold, 2 days

http://www.tf2outpost.com/trade/9725335 - 4 keys, unsold, 2 days

http://www.tf2outpost.com/trade/9724050 - 4 keys, unsold, 2 days

http://www.tf2outpost.com/trade/9760423 - 4 keys, unsold, 1 day

http://www.tf2outpost.com/trade/9759420 - 4 keys, unsold, 1 day (with an engies killed attached)

http://www.tf2outpost.com/trade/9754673 - 4 keys, unsold, 1 day (with a low-health killed attached)

http://www.tf2outpost.com/trade/9634309 - 4 keys, 1 willing buyer

http://www.tf2outpost.com/trade/9552577 - 3.75 keys, at least one sold, 2 still in stock

http://www.tf2outpost.com/trade/9586467 - 3.5 keys, unsold, 1 week (probably he changed the price not so long time ago)

http://www.tf2outpost.com/trade/9784762 - 3.5 keys, still new trade

http://www.tf2outpost.com/trade/9734170 - 3 keys + 1.66 ref, unsold, 1 day

http://www.tf2outpost.com/trade/9767450 - 3 keys, still new trade (but it's a key less from the current price, 16 hours and still no takers)

http://www.tf2outpost.com/trade/9491686 - 3 keys, 2 willing buyers

http://www.tf2outpost.com/trade/9686152 - sold for 4 keys

http://www.tf2outpost.com/trade/9718176 - sold for 3.75 keys

http://www.tf2outpost.com/trade/9722578 - sold for 3.5 keys

http://www.tf2outpost.com/trade/9636597 - sold for 3.5 keys

http://www.tf2outpost.com/trade/9652647 - sold for 3.5 keys

http://www.tf2outpost.com/trade/9658272 - sold for 3 keys

http://www.tf2outpost.com/trade/9661072 - sold for 3 keys

http://www.tf2outpost.com/trade/9700700 - sold for 3 keys

http://www.tf2outpost.com/trade/9535090 - sold for 2.5 keys

Buyers:

http://www.tf2outpost.com/trade/9772234 - got an offer of 3.5 keys, rejected it

http://www.tf2outpost.com/trade/9663864 - bought few knives at 3 keys, not buying anymore