The random vet bills are what will get you. If you want to get pet insurance shop around, for sure. We don't have pet insurance on our guy because he already had urinary problems, and they don't cover pre-existing conditions.
His food is about 23 dollars for a 4 pound bag (special urinary formula). That bag lasts a couple months, though it might last longer if the dog didn't sneak in and eat it if I'm not careful.
We spend maybe 10 dollars a month of flea prevention (frontline)? I'm not sure how it breaks down per month.
His annual vet visits run close to $200 dollars...but he's 11 years old, and with his history of urinary issues I always do bloodwork on him, too.
His litter is currently costing me about 10 dollars every 3 weeks, but that's because I'm just changing the whole box weekly, instead of scooping. Bending over to scoop is not going so well with my ever-expanding belly.
He's long-haired so he gets shaved down every year or so- that probably costs around 50 dollars, but it really depends on the place.
Other than that it's mostly just treats and toys, which don't cost much.
BUT, those crisis vet bills? Wowza. Let's see, I got Squirt (yes, Squirt... with the blocked urinary tract... Squirt can't squirt sometimes) when he was 5 years old because his previous owners couldn't afford his vet bills. I was working at the vet at the time. I seem to recall it being over 100 dollars for us each time he got blocked, and that was with my discount (at, or just above cost). We had a PU surgery done where they removed his penis and rerouted his urinary tract, and that cost about 250 dollars, but I seem to recall that it would've been at least 400-500 if I hadn't worked there. Even with that he still gets UTIs (though thankfully no blockages) occasionally, and that usually costs at least $100-200 dollars now that I don't work for the vet. Luckily he hasn't had any issues with that in a while. He gets randomly itchy skin every year or two and has to go get a shot for it... going to get one Saturday, actually. I'm guessing that shot alone will be around $40 dollars, without any physical exam.
About a year and a half ago we got his teeth cleaned, his vaccines, blood work, etc for about $500 dollars.
Anyhow, my cat is a bit of an extreme, but certainly I've been lucky, too, because the costs have been spread out over time, so far.
If you go the pet insurance route look for something that covers urinary/kidney issues as well as dental cleanings. Urinary issues are common in cats (especially males, and especially fancy breeds- Squirt is a himalayan).
Also, see if you can find a vet that works with one of the no-interest pet credit lines. Obviously if you can't afford a monthly payment it's not going to do you any good. But they can be GREAT if you end up with a crisis. They'll usually give you about 6 months of no-interest loan, if you qualify. It's not like a credit card you apply for in advance, but rather something you get if you need it. But not all vets know anything about it/work with it.
Oh- I just want to add:
Squirt is worth every penny.