How cool!
I figured this would be an easy one: Lowes and HomeDepot carry a random controller for single lights, but I've not been able to find something that I'm sure will work for you.
The closest I got was the Plug in Controller/Timer halfway down the page
here.
Something like
this might work, too.
If someone does not come along to point you to one that will work for sure, give a local RadioShack a call and ask them if they've got something in their commercial catalog that will work.