I'm glad you posted your question.

9 is an 'older' cat, but my goodness - I have a cat that is 18 years old and still plays! My cats are indoors-only and love to play with mylar balls (the crinkly kind), they love catnip, and some of them like jingle-balls. Almost every day I tie one of the mylar balls to a string and let my cats chase it and bat it - they are wild for that! I have very little money and cannot afford expensive gadgets...many great cat toys are so cheap.

Check these out, for example:

https://www.amazon.com/Chiwava-Crink...lar+ball&psc=1

https://www.amazon.com/18-Pieces-Kit...oy+jingle+ball