i am 51 years old. my mom likes to tell me how to spend my money...that i shoulnt have bought that or spent my?

How she is now is how she is probably always going to be because people change only if and when they want to change and she likely sees nothing wrong with her behavior. I think that is just your mother's way (unfortunately). If you live with her, move out and if you don't live with her, try not to tell her how much you spent on this or that. If she asks, just say you don't remember and change the subject.

She is your mom, and it's good to treat her with respect. Then again, you are clearly living in adulthood. I would tell her sincerely how you feel, still regarding her feelings, but being true to yourself as well.

Think she will sell me things under her bed so i can post them on craigslist

she is your mum and always will be thats what some mums are like,its not a matter of rights its just something you must sort out or ignore it

You should consider moving out.