http://backpack.tf/profiles/76561198176641695#!/compare/1483747200/1483833600 - sale is probably around 110 keys in unusuals, but both would need a mini

http://backpack.tf/profiles/76561198042630249#!/compare/1482883200/1483228800 - sold for a nebula hfoha, which would come around 90, but it was used to price the hat.

http://backpack.tf/profiles/76561198099031188#!/compare/1481760000/1481846400 &http://backpack.tf/profiles/76561198126204929#!/compare/1481760000/1481846400 - not sure how many keys it sold for exactly, but it could be anything from 90 to 110.

Either way the 100 pure sale takes priority over those others, and most I could imagine would be a range of 90-110, which would still lead to the same mean, that's why I'm accepting this.