Seems like the things my cars like are the ones that are free...
- empty Tim Horton paper bags - balled up so they can chase them
- pop bottle tops - they skid across floors so easily
- empty toilet paper rolls
- a backpack left on the floor for them to investigate
- a tent made out of a blanket someplace new
Of course, all this was discovered after many pet store toy purchases!
The only thing that they still like that I bought are these hard plastic coiled springs. They fly across the floor when batted and are easy to pick up in their mouths and they can stick their paws in them.