We finally launched the store to the public at large after what seems like an eternity in development! Andy's Custom CSS Editor is the first product there, and priced at $15/year it's very reasonable. Feedback has been positive mostly, although mixed at times.
There does seem to be some confusion about the CSS Editor, you can modify the css of any of the existing themes by taking advantage of the "cascading" feature of CSS. The styles you define in the editor override those in the theme's stylesheet.
I can't wait to see what people do with this. I hope to see a lot of talent come out of the woodwork and make their blogs prettier and unique!