Even though I only have two cats, I thought I'd reply.

I have a piggy bank in which I deposit all my days leftover change and regularly put in large chunks ($20-50) so if I have a high vet bill then I am not incredibly worried.

Soni was a rescued stray and Isis was from a litter than an acquaintances cat had birthed. Soni has had his inoculations and was given his heartworm/flea preventative yesterday. The vaccines cost $40 plus a $20 booster. The preventatives are $15 each but come in boxes of six. Isis has not been inoculated, yet. She does get the preventatives, though. We spend about 30 dollars on food (Royal Canin hairball formula) and about 15 dollars on litter (Feline Pine) every month. Throw in ten bucks for treats and five for canned food.

Our vet is very nice, knowledgeable, and reasonably priced. But having the piggy bank helps!

Edit: I forgot to add that Soni has been to the vet once a month since we've had him for one reason or another (He will be one year on summer solstice and Isis is ten months) and Isis has had a couple. I will probably take them in for wellness visits twice a year, still. I have never had vets ask me for fecals so I've never brought them in.