It's a valid reason/excuse in the current economy.
I could spend $10 a month to see a movie, or spend $15 a month to grind dailies, or spend $30 a month on a super cool cable hookup that can livestream me events like blizzcon. Hell, even in gaming right now I could plop down a one-time fee of $30 and have just about any game I wanted from Steam.
On that Steam note, I've been having a lot of fun with Garry's Mod. And that's a 1-time fee of $10.