Notes:

- In several of the trades, the owner lists a c/o of a Burning Anger. All of the trades that list this c/o apparently had the Anger offered by one person, who has since apparently traded it for a Burning Lucky Shot. The Anger is no longer in the offerer's backpack.

- Trade 6892672 has an offer of 20 buds, but it cannot be substantiated using backpack evidence (ie; the guy offering does not have 20 buds or anything worth 20 buds in his backpack).

- Most of the trades that had hats worth more than 20 buds offered (including a Scorching Bubble Pipe in one trade) asked for sweeteners to be added.

I put 17 as the lower range because the evidence does not point to the minimum range going up. There are still plenty of offers in the 17-19 bud range on these trades, and they appear to be serious offers. 20 flat would imply that no offers on the hat are ever under 20 buds, which is simply not the case here.

EDIT: In case you were talking about the one offer of 20 buds on one of the trades, that offer cannot be substantiated with what the offerer has in their backpack (no unusuals and no promos).