Preorders were $5, at least by the time I bought (in alpha), which IMO is a much more justifiable price for an impulse buy that might not work out. It was raised to $10 after it hit "beta" (which was after it was already popular and had made at least a million, IIRC).
Even $5 was surprising, as most people on TIGS just post their demos and games for free- back then, most people made games with the only intention of making something cool. It's only recently that everyone builds a game with money in mind, and Minecraft was amongst the games to start that trend (remember, this was before Kickstarter et al.)
