I've only used free themes so far, and seem to have no problem finding them that work for my needs. I like the Magazine Basic, which has a very adjustable newspaper-style main page. Simple Balance 2.2 is another very adjustable one I like, though it has some design issues I've had to tweak, like a mandatory sidebar graphic. I love ComicPress, which is designed for online comics, but I think has other creative-- and marketing-- possibilities. I suggest doing what I do and set up a subdomain for trying out WordPress themes and plugins before going live on you main sites.