Only professor fizzwizzle comes close in my mind in terms of quality independent, inexpensive games.

Niggling soapbox: My only complaint is that although the rendering is gorgeous 3D, the puzzles are basically 2-dimensional. I'm sure it would make the interface really hard to use (bad for a game), but as long as it's going to be 2D, I actually don't mind 2D graphics (like Fizzwizzle, and the old "incredible machine" games).