I have one cat, a male.
General weekly/monthly costs are:
Wet food £3 a week (whiskas pouches)
A couple of cans of tuna for a treat £2 a week
A box of go cat biscuits £2 a week
Dreamies/felix treats £2 a week
Pet insurance £12 a month
Flea and worming treatments around £30 every 3 months
Toys, new scratch post each year maybe £40
Annual booster £35 a year
When we first got him, we had to get him a full set of jabs, a health check and neutered (he was 10 months old when we got him) and that was £120. Also a cat box
He is an outdoor cat as in he goes outdoors but not heaps, just for the toilet and if it's a nice day so we don't have litter or anything to buy. He had to stay indoors at first as he was rehomed from a horrible home and we did need a tray and litter then but once he was going outside, the litter tray went. We have a litter tray, litter and a scoop away in a cupboard if he ever needs it when he's ill for example or needs kept indoors for whatever reason