$35. One pro-theme. Though a very nice theme, in the end it didn't work well for what I wanted my site to be and from that experience I learned that I would only be happy building my own theme, which I did using the Thematic Framework. It's nothing earth-shattering, and I'm still refining it, but I like being in charge of the whole thing, from Masthead to Footer.

I'm a graphic designer, so having a custom look is important to me. Though I'm not a full-time web developer (I work mostly in print media), I know enough to either get my work done or dig a very deep hole to climb out of (I've had experience with each). Additionally, I like mucking around with BBedit - working in code is a nice break from print design and illustration work. Variety is what keeps work interesting, IMO.

I no longer buy themes, but I'm more than willing to spend a little for a useful plug-in.