First thing now is not the best time to start a phone repair business, screen prices are crazy expensive, leaving little profit. Just 5 months ago a iPhone 5c screen was $30 now that same screen is $70. The main thing you need to stay away from eBay or Amazon that stuff is all junk, you might save some money but that stuff you fix, will be returned. They used cheap refurbished parts which will only cause you problems. I would be willing to provide some help, if you plan on doing iPads replacement screen quailty is so important because using cheap stuff will result in dead spots and ghost touching on the screen, and a big pain in the butt. Email me and i will try to help you out, I have a mobile repair business.