Since I've ran out of Mongolians to price, I guess I'll just do other low-tier Heavy hats for the time being.

http://www.tf2outpost.com/trade/20808859 - Purchased for a Miami Nights Prince Tavish's Crown (2.5 * 0.9 = 2.25 rounded to 2.3). Polar tells me to value the hat at 2.5 buds, as that's what the current owner is selling for, so he couldn't have valued it for more..

http://www.tf2outpost.com/trade/20221051 - Sold for a Level 1 Max's Severed Head. The buyout was 2.3 buds, so it couldn't have been a straight 1:1. Polar tells me at least 5 keys were added? I'm not sure (and navigating through all of the individual keys in his backpack history is hellish), so I'll just go with 2.3.

Both of the two current trades for this hat on the market have a B/O of 2.5 in pure. There's the one listed above, and there's also this trade: http://www.tf2outpost.com/trade/19346262