Well, I for one, would be interested in seeing what you've done. You could start by posting some pics of the interface you've created.
1. is it a complete audio solution or does it require another player such as winamp to to work?
2. Is it made for people running graphic lcd or character lcd or both?
3. How cpu intensive is it? There are a number of people running machines based on p166, 200 etc...
As for the prospect of making a little money for your time, I definitely support it. There are a few other members here charging for their talents.