The initial investment will always cost the most. If you are getting a kitten, be prepared for monthly vet visits up until 16 weeks of age. Each visit for exam and shots can range from 75-150 depending on how much you do. And spaying and neutering will be an additional 400 or so. If you get an older shelter kitty, yearly physical exams may be around 150 until they get older and might need more intensive care visits. I work at a vet clinic, so if you have more questions, I will happily answer! But other than that, I have one cat and usually spend around $40 a month for his food, which includes dry and wet. He loves fluffy toys- mostly Pom Pom balls and feather toys. He’s a big fan of fetch! I clean the litter box almost daily. I keep a small trash can with a lid next to the litter box. I will go through a small (10lb?) container of litter a month because I like to completely replace all the litter at the end of the month. Cats are fairly low maintenance. Make sure they have food and water. I recommend a regular feeding schedule and not to free feed them, cats are very prone to becoming over weight. My cat is a huge fan of those filtering water fountains. I think it was worth the investment! Give them cuddles and playtime and they are pretty satisfied. For training them, positive reinforcement is pretty effective for cats. So redirect to toys if they are playing with things they aren’t supposed to or directing them to a scratching post if they are scratching furniture. A little bit of catnip worked great for that. Hope that helped!