Looking for a cheap pet? Consider a fish, but keep in mind they have $200 worth of extras including bowls or aquariums, pretty decor, and water kits. Then you have dogs, the overall most expensive, ranging from $367 in food and treats, but zero in the extras. While cats are cheaper then dogs, their extras hit hard when buying litter. And who knew that grooming for birds can be rather expensive? We love and pamper our pets, but here's the real cost.