Personally, I'd go with my regular vet, if that's a possiblity. The low cost clinics often use injectable (ie less safe) anesthesia, which takes longer to recover from, they don't intubate (which gives you an airway in an emergency), and don't use much in the way of monitoring equipment. Yes, if you have a young, healthy animal, you can probably get away without those things, but your animals are at greater risk if there
is a problem. Not all low cost clinics are the same, so you may want to ask questions.
If you simply don't have the funds,(and who the heck has an extra $700 laying around?) and that's your only option, then do it, but is there a possibility another vet in the area can do it more safely, for less than your regular vet?
I work with a tech who, until recently, worked part time at a low-cost spay and neuter clinic. It is an assembly line of animals, with little or no monitoring equipment, and several animals to one person recovering them. It's a good resource to have for people who have no other option, and most of the time the animals do fine, but there is the occasional loss. Most of the time, you get what you pay for.
As for pain medication, back in the old days, the theory was that pain would keep a post- surgical patient quieter and less likely to do damage to itself, and also, that they didn't feel as much pain as we do. We know now that they DO in fact feel pain, but are just better able to hide it.
Think about it this way: If you or your child had major abdominal surgery, would you want them to have pain meds? I sure would. Old or young, I want my animals to have the benefit of pain medication. Heck, when one of my chickens was attacked by a dog, her vet gave her pain meds, too.
You have to decide what you are comfortable with vs what you can reasonably afford. It's a tough decision, especially in this economy. Believe me, I KNOW how expensive vet care is these days. But kudos to you for doing it, whatever route you choose. Good luck