Well, the first thing might be to find an old fashioned Yellow Pages and start calling and asking for price quotes.

Second, as long as the cat is indoors (and providing you don't have an unneutered male at home) - you can certainly keep her inside; she'll just be really annoying every once in a while. (If your cat is in heat - trust me, you'll know )

Finally, although I've never done this "procedure" - I understand that a female cat can be artifically stimulated and this will end the heat - for the time being. I don't know of anyone who has done this - its one of those things I read in a book once.

Good luck!