Eric, there are lots of remote and remote sensor combo's available at cheap prices. I bought a 4 button remote controller with 2 buttons for arming my alarm system and 2 spare with relay contacts. I use 1 contact to trigger the garage opener, and another to turn on my outside lights. I've scrapped the original remotes as I now have one remote that does all (compact as well) The cost of the unit with 2 remotes was a bit over $100. The remote I bought had 2 buttons of the 4 outputs adapted fro the alarm system, but there is also a 4 relay output model.
This is the remote Kit I bought. This is a
"3rd Party remote kit" I've had the units for eight years with no problems apart from a battery change.