wonder why it takes so much for my feet to hit the floor in the morning.
My dad taught me long ago, that if you aren't going to make some money there is no sense in going to work. You have plenty of stuff to do at the house.
As far as rock auto and the like, I doubt your sign makes any reference to being rockauto. You don't bring eggs to the diner for them to cook, therefore you don't bring your own parts to a repair shop.
If you are so proficient with the interwebz, look up the repair on youtube and fix it yourself with your rockauto parts. See how that works out for you.
Auto repair isn't for the faint of heart. Most get it apart and cant understand how to reassemble it back to where it works.
You might need to 'fire' some of your customers. If you are not collecting the money you are not running a business, you are conducting a charity. It is usually a good thing as you have his parts and service and he has your money. You just have to get together and make the transaction.