Mind if I join in here? I have two indoor only cats and they are my little babies, so I love to talk about them!
Cost wise, I don't think cats cost a lot to take care of. We take both of ours to the vet once a year for a general check up and to get vaccinated and wormed. It costs about $120 each for that. In between vet visits I worm every few months and also de-flea, just in case. That's pretty cheap - maybe $100 between the two of them each year. They are both registered and microchipped as it is council regulation around here, and I worry just in case they should escape one day by accident.
For food we do buy the tinned supermarket food, but we get their pellets in bulk from a rural supplier. A massive sack of it costs $50 and lasts us for months. We buy treats occasionally from the supermarket too.
We have 4 cat trees (scratching posts!) throughout the house. The cats love them, and they sharpen their claws on them and sleep on the top. We do not have any scratches on our furniture at all. We have one male and one female cat (both desexed) and neither have ever sprayed urine in the house. We have two litter boxes in a little separated room in the house and I clean it out every day. If I'm home I do it twice a day. The cats always use their trays and if they do poos it does stink for a little while but they bury it in the gravel and if you scoop the litter daily the smell quickly disappears.
We are not big travellers but will go away for weekends. If that happens we just load their food bowls up and put out extra water and they are fine when we get back! If we went away for longer than 2 days we would get a friend in to cat-sit them, just to give them some company and to clean out the litter boxes for them.
Be aware that if you have cats you will forever be playing bed tetris and more likely than not they will worm their way into your bed and always stretch out so you have no room! They also like to sit on your hands when you're on the computer, ha ha!
Honestly though, I love mine to bits and would never want to be without them. As renters we have never had any issues when we mention we have two cats but we are always up front and honest about them so I guess that helps.