I know this is *way* overkill, and I'm only suggesting it because it is the only idea I've got, but here it is:
Use our Robot Controller and components. A Spike relay would provide 12 volts, depending on how you had it programmed.
This is going to blow any budget you might have and it, like I said, is way overkill, but I don't have any other suggestions. Oh, and I'm not sure what the range on our radios is like. I've never seen it above 100' but I haven't tried.
Good luck on your project,
JBot
EDIT: Here's the link:
http://www.ifirobotics.com/