Have you ever paid good money for a cat toy and within six hours, the toy is lost or destroyed? A project posted on Instructables demonstrates how to make a cat toy out of cardboard that's just going to end up in the recycle bin anyway.
Instructables page has a template to help you get the shapes and slots right for a mouse, but I'm not sure how much the cats will care.
One sturdy cardboard box could be re-purposed into at least a couple dozen toys. You could cut all your A parts and B parts at the same time and store them in 1-gallon resealable bags. When the cat needs a new toy, pull one from each side and slide them together.
These toys are cheap and easy enough to make that you could whip up a batch and take them to your local shelter to entertain the homeless cats or give them as gifts to your cat-loving friends.