http://backpack.tf/classifieds/search/221/11/0 - Many unsold at 6 Keys. One at 5.6 Keys.

http://www.tf2outpost.com/trade/10653001 - 6 keys - 1 Day, no offers.

http://www.tf2outpost.com/trade/10614265 - 6.2 Keys - 3 Days, no offers.

http://www.tf2outpost.com/trade/10589107 - 6 Keys - 4 Days, one offer of a lv 42 team captain (not sure about the value).

http://www.tf2outpost.com/trade/10645502 - 5.6 Keys - Same guy of the classifieds. No offers.

http://www.tf2outpost.com/trade/10462406 - 6 Keys. This one have an offer of a S. Sapper (5.5-6 keys). And another one said will collect the keys. I'm not sure about it since in the trade there's also a SF. Fish. The guy said s fish.

http://www.tf2outpost.com/trade/10585144 - 6 Keys - A guy is collecting keys.

http://www.tf2outpost.com/trade/10595328 - 6 Keys - 3 days, no offers

http://www.tf2outpost.com/trade/10623678 - 6 Keys - Offer of '"if you add 1 ref"- Added to discuss

http://www.tf2outpost.com/trade/10661559 5 Keys + 3 ref - No offers

http://www.tf2outpost.com/trade/10583767 - 4 days old - 6 Keys - Offers: 6 keys if you add 3 ref

6 Keys if you add 1 ref

5 Keys

Conclusion: This item is really hard to sell since there is a Festive Replacement for the same price. The 5.6(low end) came from one guy from classified and from the another one who is selling for 5 Keys + 3.00 (1 ref = 0.2 keys) the high end (6 keys) came from the guys who want to buy and are collecting keys ( about 2 guys, and almost all the market, who is selling for 6). I know selling=/= sold, but well. There aren't much offers on this item.