Prefab garages typically cost less upfront, often between $5,000 and $30,000, depending on size and materials. They may require upgrades like insulation or finishing, which add to the total. Custom-built garages cost more initially commonly $28,000 to $52,000 or higher but they usually offer stronger construction, better curb appeal, and higher resale value, which can make them more cost-effective in the long run.