There’s no point in charging more than rescue organizations in the area charge for adoptions. If it’s not cost-effective to get a pet off craigslist vs an area shelter, who would bother? I’d be willing to buy a vet voucher for up to $150, but straight cash? I’m not going higher than $75.
I’d vote no more than fifty dollars. I rescue cats and I usually charge $25 or so per cat. That doesn’t nearly recoup my costs ($85 for spay/neuter and checkup, $40 for shots and booster shots for each cat, plus cost of feeding, grooming, other medical care) but it weeds out people who are just looking for an accessory or a toy for their kids. I put the money into an envelope to go toward expenses for the next rescue.
No, it’s closer to $200. If it’s a large dog it’ll be more–I spent $350 getting one 85lb dog neutered, vaccinated, microchipped and checked for worms.
Why? Someone has a pet that they can’t or won’t take care of any longer. I’m able to take over the responsibility for them. I should pay them for their miscalculations?
Classified ads for dogs and cats are in every newspaper. Why would Craigs List ban pet ads? 
The first place that I look for a pet is my local paper.
My local Humane Society does regular events in which they give away older than 1 year, mixed breed dogs and cats for free. They come microchipped, spayed/neutered, and with all shots.
Because you are receiving an animal that is desexed and vaccinated. That is a cost that you would have had to bear if you bought a puppy from the puppy store. Presumably you want an animal? And if you couldn’t find a suitable one on Craigslist you would be buying one from a breeder? If the cost of desexing and initial vaccinations is too much then you probably shouldn’t be getting a dog.
If you buy a car off someone and it has new tyres and a recent mechanical check, you should pay at least that much for the car, regardless of whether the owner is selling it because they can’t handle the responsibility of car ownership.
A car is a machine, not a living thing. A cat or a dog is a living, breathing creature capable of enduring great suffering. If I could no longer take care of my dog, and I knew someone who would take him for $50 and would take good care of him, even though I have spent thousands of dollars on him in the last 10 years, I would let them have him. My costs don’t matter, the welfare of the animal matters, and that’s the bottom line.
Well sure you can ask whatever you like of course and in situations like that both parties are getting a bargain.
I only read your first link, but there I read that all providers of pets for research purpose are licensed and divided in two classes. Class A providers breed pets specifically to be used in research. Those arent relevant. Class B providers are only used when it’s useful for research purpose to have “random” animals (or larger animals, or older animals, etc…). Still according to the article, there are about 1000 of them in the USA. The overwhelming majority of them are otherwise directly involved in pet-related activities and the animals they provide come from said activity.
The author finally mention that only 11 people aren’t, hence might provide animals taken from shelters, given by individuals, found, etc…and one of them had his license revoked, which leave us with 10 guys in the whole USA.
So your link in fact shows that any (potential) issue is going to be extremely marginal and that your pet is probably more likely to be struck by lightning at the moment you hand it to a stranger than to be sold to a laboratory.
Again, I didn’t read the two following links.
Oh, and I voted “cat free” and “dog free”.
Cats because in my personal experience, they find you rather than the other way around, by roaming around your place, accepting some food and finally deciding that your couch is more comfortable than whatever they were sleeping on before.
Dogs because over here, neutering isn’t nearly as widespread as it seems to be in the USA, so a dog would typically come from someone you know or a FOF who’s desperate to find willing adopters for the surprise litter. Basically if I wanted a dog, I’d just tell so to people I know, and I’m pretty sure one would materialize in short order.
Lacking a free pet coming out of the blues, visiting the nearest shelter would be my first move. Why bother searching through adds? And if for some reason I had nevertheless answered to an add and been asked to pay by a random individual, I would have assumed until I read this thread that he just intended to make money.