I ordered the Comagination modulator without the relay. This was at the company's suggestion after hearing about my intended uses (adding a 12v socket for GPS). Their take was that the additional power draw didn't require adding the relay. [url=http://comagination.com/modBulb.htm]Model number ss115H4 for $69.95.
After I install it and use it for a few weeks, I'll report back on any useful findings.
Cheers