When my brother, Dick, and I started trying to get his cats spayed/neutered, I checked the internet for discounted prices and found AZ Cats and Scottsdale Strays, but we really needed even more of a discount due to the large number of cats he needed to alter, and I found the Maricopa County Animal Care and Control website offered a FREE voucher program called the "Big Fix" for "low-income residents" to get their pets spayed/neutered (see link under "Cat Info Links"). The website mentioned AHCSS eligibility, but the form asked for information about why the applicant was requesting assistance. Since Dick was living on an Army pension plus a small VA disability payment and Social Security and working only part-time at Petsmart for retail wages, I ventured to apply for him and was happily surprised when the vouchers came in the mail for him. The vouchers covered the total cost of a spay or neuter for each of the cats we applied for; it did not cover the cost of pain meds for the females which we covered.
We chose the Mesa Spay/Neuter Clinic at Southern and Gilbert because we had used it previously (as a discount payment clinic) and had been very satisfied with the results. It is hard sometimes to get through on the phone to make an appointment, and appointments are often scheduled weeks ahead when you do get through, but the staff and doctors are friendly and competent, and their prices are great (even without a free MCACC "Big Fix" voucher). This worked very well for a few months as he crated the appointed cats in the early morning (after restricting them in a separate room to keep them from eating before surgery - this was hard for Dick to do since he felt sorry for them if they cried to get out of the room, but he knew it was necessary). Of course, this meant that I had to get up early also since I was his transportation. He had a pickup truck and we didn't want to transport any of the cats in the back of the pickup, so that meant we needed to use my 4-door Honda and get to the clinic by a little after 7 a.m. -- NOT my favorite time to have to be somewhere. (Even when I work, I don't have to be there until 8 a.m. -- gripe, complain, whine...) We'd fill out the forms for each cat and wait to be called in to the clinic room where they would weigh and check each cat over - if a cat was suffering a respiratory problem, it would be sent home so as not to infect other cats or over-stress its system. They found that a couple of Dick's females were already pregnant again by the appointment time, and if I hadn't been there, Dick probably would have taken them home to wait for more kittens, but I was strict about them being freed from further motherhood.
I have now found another clinic - the M.A.S.H. mobile unit that schedules visits at the Apache Junction Animal Control parking lot as well as visits in Tempe, Glendale, and Pinal County (see link under "Cat Info Links"). You have to make appointments for spay/neuter services, but if you need vaccinations and/or testing for Leukemia/FIV, you can just show up between 9:30 - 11 am and they will provide those services. Prices are a bit higher if you don't have the animal spayed/neutered when you get them vaccinated, but it is still less expensive than using my regular vet -- whom I adore and respect, but cannot afford when I'm trying to get a dozen or more cats served. There are always a number of folks at the MASH unit when I go, and we all agree that it is a great service.