First trade doesn't indicate the listed trade at all, if you're using backpack histories you should be providing that as well.

http://www.tf2outpost.com/trade/15283736 - Had offers of 3 pure and 3.5 pure over the past month, which raises a bit of concern over the use of the 2 month old trade for the 2.5 low end

Not to mention that the belt being used in this suggestion has passed hands a good number of times. Was there truly no other relevant information to present? Just looking at one of the other belts on the market quickly led to this sale

http://www.tf2outpost.com/trade/15192745 - Sold for 2 buds + 2 Bill's + Big Kill, which was roughly 3.33 buds at the time of the trade

http://www.tf2outpost.com/trade/15596988 - offered 50 keys, claims to have sold for 3.5 pure

http://www.tf2outpost.com/trade/15505435 - this hat offered on cloud9 robin (2-3)

http://www.tf2outpost.com/trade/15523991 - seems to have sold for hearts robin (2-2.5): http://www.tf2outpost.com/item/440,2065718248,314,5

However, these three plus the two links you have are all for a duped version of the hat.

http://www.tf2outpost.com/trade/15697529 - offered roboactive halogen (3.5-4)

Vincent's posted sale of 3.33 is also for the clean version. It seems the clean gets better offers/sales than the duped ones.