Check to see if there is a robotics club in your area. They will likely host or attend competitions for mini-sumo, fire-fighting robots and many other competitions that are quite inexpensive (relative to FRC, or even FTC) to enter. The Western Canadian Robot Games, (
http://www.robotgames.com/) is one example of such a group. I know there are also active robotics clubs in Vancouver, Portland and Seattle, so google up one close to home and drop by a meeting.
Jason