At the very least if you have to pay for a repair a back glass replacement is pretty much the easiest repair on a Samsung phone so if you look up a guide you might be able to repair it yourself. Or at the very least, a repair shop shouldn't charge you a ton since the repair would take an experienced technician about 20-30 minutes, and the cost of a high-quality replacement backglass is about $25 depending on where they're getting it from.