I believe that the only things your could spend serious money on for your cats are their health, their food and their cat tree. I often shop on clearance to try anything new and if your cat is anything like my bub, you will often find dog toys reclaimed from your mutt that make them totally happy.
They are also perfectly ok with used wares from Craigslist. Be sure to check items for fleas and things and clean them first.
Tommy has a toy box now. I found my largest, sturdiest shoe box lid off a fancy pair of Marc Jacobs that I haven’t even worn and loaded it up with his toys while picking up around the house. It’s tucked under the guinea pig pen. He took a nap in it last night and today half his crap was back out around the house.
I love my dog cat.