The kitten shots, and later fixing and possibly declawing can cost a lot- but not as much as letting the cat get sick would.
If you get your kitten from the SPCA, they might help you with the vet bills. Around here, the bills tend to run between $70 and $100, with more for emergencies. But this is without aid, and in an area that's a bit pricey anyway.
You'll want to talk with your vet to get a better idea of your costs.
When you bring your kitten home, you will want kitten chow, a food bowl, perhaps a water bowl that your kitten can't tip over (we had a huge problem with our latest pair doing that), a litter box, and maybe a couple of jingle-ball toys. And don't forget a scooper. For litter, we use a clumping kind: That's easier to keep clean than clay litter.
You may even want to train your kitten to wear a harness or collar, but that's optional if your kitty is going to be strictly indoors.
Congratulations, and good luck!