How are taxidermy shops able to sell human remains?

I went to a taxidermy shop in San Francisco that had a wet specimen human brain for $7000.

Today I went to one in Phoenix that was selling bones and even a whole skeleton, also for thousands of dollars.

How are they able to do that? Are there no laws surrounding it? How are they even getting human remains to sell?? It feels ethically and morally weird to me. I was looking at the brain in SF and just thinking about how someone’s entire life is in there, and now it’s being sold for $7k at some random store. I feel like I wouldn’t be happy about that if it were me 😅