Hi there, I share your concern. I have a 10mo old female and 9mo old male who will be neutered/spayed on the 15th of June. I am have to admitt I am nervous about it..
I asked had all the same question a few weeks ago and this is what I came up with.
I was told the best anestesia to use is isofloraine (sp), be sure your vet does a blood panel on them before the procedure to make sure all levels are OK.
If you are looking for low cost you can try
www.friendsofanimals.org they offer Spay/Neuter Certificates that will give you a considerable savings at a participating vet office. My girlfriend just used the coupon and said the spay was $10 total!
If you are looking for a low cost spay/neuter clinic, you can contact your local animal shelter or SPCA and ask them for info. They usually have their animals spay/neutered at the low costs clinics so the should be able to refer you.
Good luck!!