If you don't want to spend a lot of money, I'd keep my eyes open on Craigslist. People are always redoing their kitchens, so you might be able to find some old cabinets, countertops, sinks, etc. for nothing more than the gas to go pick them up. I've seen stuff listed in the local papers, as well. Is the garage attached to the house? Do you have a water line in there?
Keep you eyes open for old fridges, too, you won't want your fermenters exposed to the temperature changes most garages go through. I've never done it, but a lot of people here have hooked up external thermostats to old fridges either for lagering purposes or just to maintain a consistent temp in the high 60s. I am assuming that if you are setting up shop in the garage, you want EVERYTHING in there, you don't want to be lugging carboys into and out of the basement.