Dinosaur fossils aren't usually worth much money, and paleontology is not a secretive science. Wherever you're getting this information from, it's just false. The mastodon bones weren't sold to anybody, they were taken to Cornell for study. Cornell usually either keeps their bones, or donates them to a museum.
A lot of paleontological research of available for free download from universities. All you need, to get permission to look at most college's collections, is a stated research purpose. You do not need credentials, or money, just a 'permission slip'. They will either just give you what you ask for (if it isn't rare) or loan it to you, if they're confident you'll return it.
Errr... this one sold for $31M https://www.nytimes.com/2020/10/06/arts/design/t-rex-skeleton-brings-31-8-million-at-christies-auction.html
Is this therefore false information?
Just to clarify, what you're saying is that in fact anyone can get their hands on dino bones to examine them?
There are some rare finds that are worth big money, just like some coins are considered rare and valuable. These may be hard to acquire.
For the most part, yes, the idea that they're all insanely valuable is false information, and yes, anybody can study most of the fossils that have been found.
Thank you for clearing that up.