Looking to decode a Composite or S-Video signal to RGB C-Sync...

Hi all! Well as the title suggests, I'm looking for either a commercially available device or even a circuit I could build that would decode a Composite or S-Video signal back to a 15KHz RGB C-Sync signal. I'm just looking to get a little more versatility out of my stand alone Arcade monitor (as in not in a cabinet). Such as general TV tuner or DVD use.

A little left field I guess, but I just thought I'd ask away none the less

Here its on the costly side

http://www.lupinesystems.com/