I worked this out based on items/unus being valued in the middle of their range, and taking around 90% of their value for overpay. I own the hat and I paid the high range (5.6) in pure.

#1 [url]http://www.tf2outpost.com/trade/13105076[/url]

3.5 pure - turned down.

Stormy Executioner (4.1) + 2 buds = 5.6 buds after Unusual overpay

Stormy Stalhelm(1.9), S. Kritz (34 keys =1.6), and 2 pure = 5.15 buds after Unusual overpay

5 buds + 12 keys (I can screenshot proof if you really need it)

Older Trade of same hat = [url]http://www.tf2outpost.com/trade/11544789[/url]

Offers

4 pure + sweets - considered and added to discuss sweets = Most likely under 4.5 offer but this person didnt get the hat

nuts n bolts nickel noble(2.3), stormy batters helm(1.6), 1 bud = 4.5 buds after Unusual overpay

power surge lucky shot + a craft 19 original = who the heck knows

No idea what previous owner to me paid.

Need other examples but it's rare on the market. Rarer than G.Fetti by a long way (G.fetti is priced at 4.9-5.6)

Offers show that 3.6 buds isn't accepted and it can get much much higher offers. 4.2 is also not accepted recently.

All comments/feedback welcome, tell me if I'm doing it wrong!