My wife and I recently adopted a pair of cats, a mother and a daughter. Both are still young, with the kitten being just past 6 months, and the mother only being perhaps a year older than that. The mother, Juniper, had the distinct misfortune of being lost at a young-ish age, as when she was found by the family we adopted her from, she was pregnant and living in a bush (hence the name).
Juniper was lucky. Catherine and I had decided we wanted a pet, but our condo's bylaws had restrictions on dogs, so while neither of us had ever owned cats before, we decided that we'd probably be fine with having cats. Plus, our lives at this time aren't really conducive to dog ownership. We spent a while watching Craigslist, and I know that when we called inquiring about the mother, the woman who was caring for the cats was thrilled. It's easy to adopt out kittens (though adopting them out to good homes, as was presumably the case with Juniper originally, can be tricky), but adult cats, even young ones...most people aren't interested.
After some consideration, we decided to also take one of the kittens, Ivy, who was one of four. Caring for one cat really isn't any more work that caring for two, and having both ensures that they can keep each other busy and entertained when we're at work or whatever. However, while we're glad to have both Juniper and Ivy, it was unfortunate that Juniper hadn't been spayed when she was younger.
For some reason, it's acceptable for many people to let their un-modified cats wander outside their homes, which has led to a major problem with cat overpopulation, as well as such a large variety of mongrel cats, that people interested in actual cat breeds have problems finding homes for kittens that are pedigreed. It's really interesting that people who'd gladly pay $500 (or much more) for an AKC registered puppy, wouldn't dream of spending more than, say the $75 Humane Society adoption fee for a cat with papers as well. Admittedly, there are a lot more cats out there needing homes, but dog overpopulation is a major problem for similar reasons, unmodified animals who are irresponsibly bred, either on purpose or not.
Even ignoring the pet overpopulation problem, which is huge, it's a major quality of life issue. We've had the cats for about a month now, and twice Juniper has gotten stressed out enough to go into heat (the first time was right after we brought her home, the second was the first trip to the vet for vaccinations). Now, I don't know if you've ever been around a female cat in heat, but it's pretty miserable, for both of you. She is obviously hideously uncomfortable, you have to deal with a cat who's going out of her way to get you to do...something...to her genitals. It's really an unpleasant time for everyone.
Now that the cats are both old enough, no longer nursing, and had their initial shots, we've taken the steps to get them spayed. We talked to our veterinarian, and got a quote from her, but it was...expensive. Now, admittedly, it was probably a much better spay, but by utilizing the Spay-Neuter Clinic in Moscow, ID, we were able to get both cats spayed (and leave a decent donation to the clinic) for about what it was going to cost for a single cat at the veterinarian.
The hope certainly is that, between what we were charged, and the extra we gave, that we'll be able to help this clinic offer financial assistance to those people who otherwise couldn't afford to get their pets fixed. Even if you don't need a spay or neuter now, if you have a bit of extra money this holiday season, consider making a donation to the clinic. It's tax deductible, and if we have fewer dogs and cats capable of breeding, we'll have fewer dogs and cats living in squalor, or having to be put down because there are simply too many animals for them all to have a home.