Collecting body parts goes back centuries. For example, embedded within every sanctified altar in every Catholic church is a relic from a saint. The first-class (most desirable) relics are body parts.

Private ownership of saints' relics used to be expressly forbidden. AFAIK it is now simply heavily discouraged. So you might have trouble making a business out of it, unless you can convince the church that you are legit.

And good luck getting permission to authenticate any of the existing ones. God specifically said you're not supposed to put Him to the test.