Brad, one of the things for you to consider is that your boss has expenses far beyond your $10/hr wage. It's easy to look at business owners and feel they are "making the big bucks", or are "taking advantage of people" however most fail to appreciate that he has a space to pay for, property tax, maintenance, workers compensation insurance, liability insurance, electricity, water, payroll, payroll taxes, equipment, product, trash, a dealers license, and trust me, the list goes on and on! Running a legitimate business can be VERY expensive! He is also the one finding the vehicles and recognizing the potential in them, he's taking the risk on every vehicle purchased, and he's sitting on the inventory (his money) waiting for it to make him money.
I'm sure the work you are doing warrants appreciation and is turning these basket cases around, but on cars at the price range you are talking about, I would be careful assuming he's making a killing. It probably won't hurt to go in and ask for a raise, but if you are at a competitive wage, don't be surprised if the answer is no. If you don't like it, go into business for yourself! It is the most stressful, and also the most liberating thing you could ever do. You will gain a whole new appreciation for what it is your boss does. Best of luck!