Only 1 on outpost.

http://www.tf2outpost.com/trade/9192789

~sold for a Sunbeam Slug (8.1~Considering unusual overpay would be around 7.5~8)

I put 7.5~8.5 buds as a base price so that it is easier to adjust in the future. But from the previous trade 8pure may be hard to get because there is no price for this hat and not everyone likes halloween effects. Price will fluctuate a bit when Halloween comes and stuff.

Also knifestorm is around the same tier as energy. The GE cm is 7.2 and the PE cm is 10.6, so i think this hat should be worth between there.

http://backpack.tf/vote/id/50b66ff3ba25365812000042

last suggestion was posted 5 months ago. But price has probably been outdated by now. He sold his for secret jumper (6.3) and a low number medal (worth 1bud)+sweets so should be around -7.5+.