Oh yes, no kill shelters have their limits, and I've never had any regrets the times we've adopted from our shelter. They do a fine job, but the reason I was looking at other options is because the shelter is so well known here, and I know they're aren't the only shelter doing work. I mean, when people want to adopt, they immediately go there, so as far as potential adopters, they are the least hard pressed, and they probably procure the most outside funds.
And yes, I totally agree that buying from a backyard breeder is definitely not the right way to go about procuring a kitten, or puppy for that matter. I can't begin to count the number of unpointed himalayans, ragdolls, and himalayan/ragdoll crosses that are trying to be sold for a couple hundred dollars. But when I think of adopting kittens on kijiji, I'm thinking of the ones that say "free to a good home" or that come with a cheap adoption fee that's like 25$. The ones where you may not be supporting responsible pet ownership, but you know they didn't do it purposefully to try to make a few dollars. Adopting from them tends to help with the over population as you'll take in a kitten, get it spayed/neutered and prevent one more from ending up on the streets, because that's where the unadopted kittens from those people tend to end up if they aren't adopted. That or the local shelter where you would have adopted them from anyways.
Either way, I do plan on supporting our local shelter, whether it's through adoption, fostering, other volunteer work, or donations. I support what they do for pets here, as it's the same thing, spay/neuter before adoption, adoption fees tend to be at about the same range (150$), and all of their cats have a guaranteed health, as in you know what you will be getting in terms of health problems as all animals are regularly checked by their vet. There's also a local TNR group looking into starting up a cat sanctuary I may look into for volunteer opportunities which might be interesting.
When I have a quieter place I would like to take in some of those kitties with a few more behavioural issues, but we'll see how things end up.