I recently built an air cannon. It works great. I needed a wireless remote to fire it and after some searching, I found a great deal at Radio Shack. It's a small box that you plug in to the outlet, then plug whatever you want into the box. It comes with a wireless remote (like a car beeper). The range is about 30 to 50 feet. It's sold as a remote controller for Christmas lights. I got two (different channels) for $28. It works great.
Bob