Ok now to clear up some questions.
No I do not have a tax license but I DO report what little income I get from doing this to the IRS hence the contract/recipt.
All the contract is is a piece of paper that describes the condition of the item when I receive it and states that I am not an authorized repair person for any one . This is just a formality to help keep me in the clear if anything legal should arise. but seeing as how 99% of my customers are your stereotypical homies that want nothing more than volume, they rarely want their copy of the contract or receipt, and 90% of them usually give me twice what I ask because I was able to save a $900 amplifier for them.
Guess it's just the one odd ball customer on a bad day that got me down?
Customers charges.
$25.00 Diag/repair
$0.25 capasitor (sold at cost. I do not markup components)
Total should have been $25.25
What I was going to charge (out the door) $25
I have no store front I do this just as a hobby and a means to fund restoration of my MR2. The 9-5 job is money for the family.