@stan2004: That's exactly what I'm looking for! Thanks so much! I didn't realize they relays could be purchased pre-installed in the modules with the screw terminals. I think that's definitely how I'm going to go about it.
I've got enough wall warts and transformers that I can send 12V to the switches no problem. I was worried about going the relay route because I didn't feel like I was ready to solder everything up, but the pre-installed modules look good to me. Are the relays replaceable on the modules if they go bad?
If you've got links, I'll use 'em, otherwise I'll start looking on my own for the above. Thanks a bunch!