Pet food. I have done a lot of research into the pet industry in general and there are a lot of things being sold for pets that are literally unsafe for them. Like cages that are too small, treats that aren't safe for them, chew toys full of toxic shit they shouldn't invest, food that is the equivalent of McDonald's every day, etc

Don't get me wrong, there's good quality pet food you can get fairly cheap and bad quality pet food you can get that is very expensive. It comes down to research. But if you're just grabbing whatever is cheapest is most likely setting you up for potential health issues down the line.

This is speaking as someone who has experienced this with both cats and rabbits. The cheapest food for rabbits is usually full of alfalfa and whatever else weird ass colorful shit they threw in there that is not healthy for adult rabbits. And cat food is usually too high in carbs, too high in salt, or both. Diabetes and kidney failure in cats fucking sucks, it's not worth it.