You can save some real money on pet supplies using thrift stores and garage sales.  Remember, don’t getting anything that’s broken or questionable.  Don’t save money at the expense of your pets.    Here are some of things I’ve spotted:

1. pet crates (This is probably the best bargain you’ll find.  Crates can be pretty pricey ($20-150), but I see them in all sizes pretty regularly at my favorite thrift store.)
2. bird cages
3. glass aquariums
4. ceramic or stainless steel pet bowls
5. Habitrail components
6. towels (for baths or bedding)
7. kitty condos
8. storage bins with lids (for storing toys or to make your own awesome litterbox)