Any pet from fish to cats to dogs to horses are not low maintenance. They all require time, care, and attention. Even 'minimum' maintenance pets like betas require more attention than a houseplant.
Dry run the least amount of time you have to contribute to a pet, think fussy houseplant (e.g. African violet). These buggers are fussy about light, soil, fertilizer, and water. Usually around six or seven dollars and are readily available. Keep it alive through at least two blooming cycles 4 - 6 months.
This is similar to baseline care for small mammals (hamsters, mice) and most basic fresh water fish.
Rats, rabbits, ferrets, guinea pigs, chinchillas, and other more exotic species (crabs, lizards, salamanders, snakes, and birds) will require as much attention and enrichment as any cat.
Cats need as much care as any dog, but many dogs are as demanding as a human toddler.
And don't be taken in by the idea cats are 'low maintenance'. Just like dogs, they require attention and healthy time investment. Brushing, feeding, litter, shots, enrichment activities, flea and tick prevention, as well as preventative care for things like renal disease. (This means feeding your pet a high quality balanced diet, not the Walmart brand cat food unless you want a $3,500 vet bill before the age of 7.)
Never consider free feeding because it is the leading cause of obesity and obesity related deaths in cats. Top complications being renal failure, urinary tract blockages, and an increased risk for cancer, and diabetes, (treated with two insulin injections every day for the rest of their life).
Many don't live to see the age of 10 due to 'low maintenance' care. (e.g. Top off a food bowl once a day. Scoop litter every other day. Refill the water bowl when you remember.)
I have one cat, his food is around $40.00 a month. He is on high protein, low carb kibble in the morning and refrigerated fresh at night.
Just like with dogs, even more so with cats, an average commitment is between 10 and 22 years, with the cost of care increasing as the cat ages.
Cats might not require walks and outdoor exercise like dogs, but they still require just as much care and interaction. My cat, Potato, actually requires more work than our greyhound, Zwi, whose personality is so laid back he is nearly comatose.
Keep food cost and vet bills in mind. Can you afford to drop $250.00 at the drop of a hat because the 'free' kitten has been vomiting for two days? I had to fork over $900 for Rue Dog when he had to have a dental because he cracked a molar on his chewy bone.
I gladly paid it, but things were tight for the next few weeks.
Other things to consider. Behavioural issues. Peeing outside the box. Scatching of inappropriate surfaces. Night time distrubances. Pet care when you have to be away from home, etc. What happens if the pet ends up with a chronic illness like diabetes or a thyroid condition? These are all top reasons cats end up in shelters.