Shelter kitties are my favorite breed!
You need to consider costs though.... the cat, litter, toys, SPAY/NEUT, litter box, premium food (not grocery store), unexpected vet bills, bowls, shots if you believe in them, tests, ect ect ect....
What kind of food do you plan on feeding? Do you have bowls?
What kind of litter will you be using? And do you have a litter box already?
Do you have a vet already?
D0 you have money put away in case a emergency happens with kitty?
Will the cat be spayed when you get it, or do you have to have it done?
Do you realize the pain of declaw? Are you prepared to clip nails ever week-2weeks? Do you have a scrathing post?
Do you plan on having the cat aids/leukimia/ect tested?
Are you prepared to care for (financially and physically) the cat for 20 year if it lives that long?
What are you going to do if the cat eliminates outside of it's box, say it poo's in your bed? Do you know the proper way of getting out the smell so kitty cannot smell it and doesn't go back due to smelling it?
If you said no to any of the above, you may want to get the suppiles/info before/when you get the cat.
May seem a bit over the top, but at the very least you need a vet picked out, food, litter, litter box, bowls, SPAYED, brushes if it's longhair, nail clippers (research first), money for emergencys, and the standard aids/leuk tests. These are necessities, no way to go around that.
Look around on the forums for info, there's plenty of it!