Alright so for those of you who want proof, here is some proof

http://www.tf2outpost.com/search/79539390 <-- alright 4 on the market where before there was like 7 guarantee

http://www.tf2outpost.com/trade/8641176 <-- b/o a tiny bit high but still

http://www.tf2outpost.com/trade/8562361 <-- declined 5 buds looking for 5 + sweets

http://www.tf2outpost.com/trade/8180509 <-- again declined 5 pure

http://www.tf2outpost.com/trade/467917 <-- b/o 6 no longer on the outpost

http://www.tf2outpost.com/trade/6335174 <-- no less than 6 no longer on the outpost

I think whoopee is undervalued but it looks amazing in game, I've owned 4 Burning Flames whoopees before and i've some experience with this hat, bought my very first one for 100 keys pure. Bought my current one for 5 buds + 7 keys http://www.tf2outpost.com/trade/8436181

http://www.tf2outpost.com/user/30086 my 2nd whoopee

http://www.tf2items.com/item/1148671334 my 3rd whoopee

http://www.tf2items.com/item/952161249 1st whoopee

http://www.tf2items.com/item/1461927597 4th whoopee

can't really find every single whoopee history but it's rising and i think it deserve the price range of 4.7 - 5.2 pure for b/o as people are demanding for 5-6 +