Never really been a fan of unusual weapons tbh. Maybe if there were better looking effects, but I'm not big on the 4 there are.

Sold for an Ancient Eldritch Hellmet(~49 Keys) and a Strange Festive Pro KS Flame Thrower(~13 Keys)(B/O was 49)

http://backpack.tf/profiles/76561197999873164#!/compare/1485907200/1485993600

http://www.tf2outpost.com/trade/28360978

Ancient Eldritch Hellmet quick mini

Sold for a Flaming Lantern Brain Bucket(Outdated at 41) and 32 Keys(~73 Keys total)

http://backpack.tf/profiles/76561198125791160#!/compare/1483228800/1483315200

Seller at 49 on classifieds

This sale is likely an outlier, but the hellmet is no doubt higher than 36. Easy B/O cap.

49 flat.

Credits to Mindacos for the suggestion. He found the proof, I'm just posting it.