Previous suggestion was missing the seller's B/O.

http://www.tf2outpost.com/trade/24036423 The seller's B/O was 100 pure, took 4-5 months to sell at that price.

It sold for the only clean Knifestorm Hustler's Hallmark. The only traceable sale for the Hallmark in the past year is the sale for the Hive Minder. It's likely closer to 100 based on some offers I looked at.

http://www.tf2outpost.com/trade/25138916 Offered duped Burning Cowl, 4 months outdated at 125-150.

http://www.tf2outpost.com/trade/26003362 Offered GE Cannonball, updated at 80-100. + a low craft #