Just read about this site in this months' keyboard mag:
http://www.geocities.com/midiboutique/#b4cp
looks like a great product. This company basically sells all sorts of midi controllers and component and they can do custom things. I've never dealt with them, just impressed by the website. Hopefully they do better than Grex at customer "support" (and I'm sure they do).
Ryan
Hot custom midi controllers
Doepfer (www.doepfer.de) makes custom units kind of like this as well.