Tax ID is cheap, but what you need to do to cover your ass is Insurance.
getting an account at Tucker rocky and those places a lot of them ask for a picture of your store front, and a minimum order of say 1500-10k in parts depending on the business.
When i was young i did this with cars/parts, nowadays you need to create an LLC(protects your personal items House, cars, saving, retirement from suits), Get insurance to cover suits so one accident doesn't take down the whole house.