Most of the gameplay-affecting weapons are $2+ each (example [1]). It's true that they are sidegrades (it isn't just pay-to-win), but its kind of disingenuous to say they cost "mere pennies"
Unintentionally a bit misleading, but not disingenuous. The market value for an ordinary TF2 weapon, on sites like http://scrap.tf/ but also in the TF2 aftermarket generally, is usually the equivalent of about $0.014 . One you have a basic acquaintance with TF2 trading, the idea of buying weapons at the official store is so outlandish that it had genuinely slipped my mind that it was even possible until you reminded me. (Even if you don't want to mess around with item crafting or trading with bots or humans, at Valve's other official item store you can buy a fancier, kill-counting version of that same weapon for 15% the price! http://steamcommunity.com/market/listings/440/Strange%20Clea... ) I suppose there must be a significant number of people still doing it though.
Ah, interesting. I haven't played TF2 since the player marketplace was introduced. It uses to be either buy from the official store or go through some pretty shady websites.