Get a tax I.d. from the IRS it is free and you can use it to become a distributor and lower your prices. Also once you get the tax i.d. you can open an LLC. for about $1,000 with legal zoom., which means a limited liability company, if your garage burns down and a customer gets severely hurt or if their car catches fire etc.. you personally can not be sued , only the estate of the LLC. I would do this ASAP and get insurance, if you or your buddy are former military or either of your parents are, you can possibly become a USSA customer (they are a bank) and you can get 1 mill. annual business insurance from them for $69 a month (that is cheaper than anywhere.)