If you don't have any luck here, take a look on Steamgifts' trade section. Its a fairly easy get for a decent price. You're literally about a week or so late from getting it at a decent price from almost any regular store since there were Bethesda sales for QuakeCon.
Theres lots of dispenser bots that have it available too (dispenser.tf). You have to have keys to get them from there though and the best price Ive seen is around 4 keys, which is roughly 8 bucks. The one issue there is you'll have to find a key seller that accepts Paypal. Its not hard to find one, just another step. There's at least one guy on SG that is offering it for 3 keys too. If you look around you'll be able to get it easy.