Building a garage, cost $$$$

Get about 5 bids. Prices vary quite a bit. You can get a slab, have soemone frame it, then you can finish it yourself. Or at least have the shell built, then install insulation and drywall yourself. Also check into a metal garage, they are a lot cheaper and they have more usable height (think lift).

http://metalbuildingdepot.com/aspx/photogallery.aspx