I like pet rabbits. You can buy them for $5 and feed them veggie scraps and let them trim your lawn. They keep the grass short rather than destroy it. Bulk rabbit food is just hay pellets and leftover middlings from processing of corn and wheat. It costs $10 per 50lb bag. They require no vaccinations and fixing them is only $20-50 for males. Females are about $200 and that’s the only big expense.
