you can try going to http://www.petfinder.org/
to see if your local shelter is online. You can search for kitties in your area, see pictures, ages, which ones are "urgent" (read, about to be put to sleep) and what type of home they would do best in (ex, no small children, other animals, etc) mny shelters charge an adoption fee, I think its like $55 per animal at our local humane society, but this fee covers them getting spayed or neutered, their first round of shots, and usually a deworming. If you don't want spastic little kittens, you should look for kitties from 6mos- 1yr old, they are still cute and playful at this age but are starting to be more independent. As far as litter and food go, be prepared to keep buying whatever you start them with. If you start with cheap walmart food and litter, keep buying that for them. Kitties can be resistant to change and sometimes down right refuse to change! I remember when we started using new litter, our kitty would not use her litter box. She would do her business in the bath tub (hey at least it wasn't on the carpet!) If you do have to change food or litter, do it gradually, mixing in a little more of the new stuff each day. I prefer to get more than one kitty at a time. We had one of ours pass recently and the one thats left seems so lonely sometimes, she has definitely become more "needy" wanting to be held and petted and paid attention to. We are planning to go and get her another friend in a few weeks and hopefully that transition will go well. Good luck on picking a new fur child, they can be so much fun and comfort!
ps. would also love to see pictures once you decide who to adopt