Is my friend possibly being abused?

It's a possibility, the only way to know for sure is to talk to your friend about it. I'm sure you'd want someone to do the same for you. Just make sure you convey that you care about her and you're not judging her. And the whole thing about money, sure some people express love with money but some people also think they're buying the rights to treat someone like dirt by buying things for that person. Good luck, and btw you're really well-spoken for being in 6th grade. :P