We have had a menagerie of animals over the last 10 years that have included almost every house pet outside of lizards including dogs, fish, turtles, hamsters, mice, birds, rats, rabbits, and guinea pigs. No cats because dad's allergic, but otherwise, we are happiest with our furry or somewhat slimy friends. At this point we are down to 2 rats, a bunny, and some fish. However, there are somethings we do now or have done that could help control costs and benefit the health of your animals.
Pet litter: For mice, rabbits, hamsters, and guinea pigs, use shredded paper. Newspaper is ok, but the colored pages are a no-no. The long shreds work best as they can burrow into it to stay warm and explore, but the cross cut works as well. Since we broke our 3rd shredder, we get donations from extended family and a recycling advocate on freecycle. Before this, I took bags of it home from the office I used to work in. Check with your local businesses as they may be thrilled to not pay a shredding disposal service. The next cheapest option was wood shavings by the bale at a farm supply store. This was about $6 each and lasted a while. For pets on a leash, we reused plastic shopping bags instead of the purchased rolls. Free again.
Pet food: For vegetarians in a cage, I approached my local grocery stores for their culled veggies. Most said they supplied pig farmers, but one was glad save them for my critters if- 1. I provided a bin and 2. If I would be faithful to pick it up on time. No problem! The critters had good, free food for quite a while. I actually ended up having to get creative with drying methods and making longer lasting items from it to not throw the excess into my compost pile. For other animals that prefer grains, some wild bird seed mixtures are cheaper than the pet store formulations with virtually the same ingredients except maybe pellets. Those can be purchased in large bags from the farm supply store as well. For birds, there are recipes for bird 'bread' that is good enough for us to eat if it weren't for the egg shells. Ask my mother in law, who mistaked a fresh pan on my oven for banana bread ;) For the dog, I made my own food, following online recipes that included the scrap meat from poultry carcasses after making broth, rice cooked in broth, sweet potatoes or carrots, olive oil, sage, parsley, crushed egg shells, kelp, and oats. He loved it and I knew he was getting good food instead of byproducts. *If anyone has tips on rat food, other than table scraps, let me know.
Pet health: I purchased food grade diatomaceous earth and we rub down the furry critters with it regularly, especially in flea season and it can be added to food for internal parasites. WARNING: Be sure to get food grade! I also made up a bandana for the dog with various essential oils that were pet friendly, yet flea/tick aggressive. Any minor cuts or abrasions calls for our colloidal silver spray for quick healing. For larger wounds, like when my mini pincher attacked the neighboring pitbull, we kept EMT gel handy (on the amazon site below).