why pay for a theme?

In every drupal cms that I have implemented, the design was done up-front and we do a custom theme for the design.  That's the way we roll.

However, for my personal site, since I am not a designer, I was considering upgrading my theme by purchasing one of the commercially available themes.  Then I discovered there are a multitude of free themes at http://drupal.org/project/Themes

While this may be super-obvious to other Drupal folk, as I said, I am coming to Drupal as a programmer, not a UI person so this "discovery" was good to make for me.