I recommend buying captive bred rays from a reputable local breeder or one that ships but only buy from reputable sources.
+1 for this. Don't get excited and buy a ray that's extremely skinny. Being a beginner it will most likely die.To expand on this try to make sure you can see them feed before you buy one. Then reguardless where you get them treat them with prazipro for a week or 2 to be on the safe side.