In the real world you have to get approved by government agencies, and your product goes under testing. Harry would have to sell it on the black market... For some things that would make him rich, but I doubt selling a cure for baldness on the black market would get him a ton of money. Especially since you can just get hair implants and grow your own hair now.
If Harry had no morals his black market product would be love potions like Susan took. Rich people who have everything except for the person they desire, but get turned down by would pay vast amounts of money. If someone is willing to pay hundreds of millions for a painting they will pay a huge price so they can possess the person of their desires.