Sale 2 probably had something to do with either PSC's or something was put on the market and paid for. Maybe even paypal too. I only say that because of the CCC and the Black Ninja Socks that are both untradable.

On your first sale, he had a BO of 80 keys (actually said " B/O 80 keys. Huge discount for pure" but I'm not sure if that meant 80 pure and more in unusuals, or 80 in unusuals with discount from 80 if pure) Either way, if I understand correctly, you couldn't count that one above 80

But that may be irrelevant, as KaW Muffs are nowhere near 100, or even 80.

http://www.tf2outpost.com/trade/26054781 --asking 50 keys pure

http://www.tf2outpost.com/trade/23119573 --asking 16 buds, which would be around 50 keys, depending on when he updated that (After reading comments, it looks like he updated buds amounts sometime in the last month, at least)

This would mean your first sale is for a lot less than 98, and your third one is the outlier, while your second sale is on the low end of normal or the high end of QS (but it wasn't for pure, so I'd hesitate to call it a QS or discount it). Also, Frostbite Muffs have a 3 month old price, which may be fine, but it is a newer effect, so it's possible those may have also come down some.