I bought a 10X20 car canopy with metal posts and a tarp top for $75 at Walmart and a full side kit with a big zip door from Kmart.com for $105, total investment $180 for a garage
Compare that to the price of a halfway decent car cover.
A good wax job will do far better than any car cover. The wind will help that cover sand the paint right off your car! Maybe it won't be that bad for one season, but it's the last thing I'd do.