Usually Dealerships pay the best, but if you have all the Certifications, you can find a good shop that pays well. My mechanics were well paid because they did quality work. That's how you make good money : Fully Certified, quality work and care. You can make a good living.
You can make good money as a mechanic by being well trained, and competent in the business. It is not easy, and it is not cheap to become a mechanic. The tools alone cost around 10,000 bucks, and the training is several more thousand too.