You've already confronted her and she still disrespects you.

My MIL & FIL did this too. What changed the whole thing is I literally gave everything back to her the next visit. I stopped making up excuses and said "no thank you"

You could also never invite her over/ always see her during an event or something so bringing toys would be inappropriate for that circumstance and would make her look bad for doing that.

Do the dance with her. Ask for specific things that are $$$$$, but whatever if shell buy it, fine. She might be offended if you ask her for large toy purchases. It's just mind games. It's not even to be mean or take advantage, it's just a reaction to constant disrespect. You can be really blunt here too. "Well clearly you can't stop buying toys although we asked you to, so I may as well tell you what is needed/wanted."

Eh, so annoying. Good luck!