It is okay to buy and sell human tissue as long as the deceased had filled out the proper consent forms. Human flesh is tissue like all other tissue, like all other donated organs, the only real issue here is if this practice follows the wishes and desires of the deceased.
I feel that it is okay to buy and sell human tissue obtained from dead bodies about to be cremated. I feel that those who are collecting the tissue should receive permission from the family of the person the tissue is collected before doing so, but as long as there is approval this is okay.
I think a humans flesh should be something that should remain on the human alive or dead, I don't think it's okay to be creating a market for human flesh and I think we should respect the dead and keep it on their bodies, even if the event of a cremtion I don't believe it's right to be doing that.
If you work in a crematorium and you're hoping to make a little cash on the side by scalping dead bodies and selling human tissue, I would think again. This practice is very much against the law and it is doubtful that you will get far with your product without getting caught. It's not okay, it's not legal, and there are plenty of moral and ethical issues with it as well.