I think some do charge just to discourage people from getting a dog without putting enough thought in. If people have to pay, they are less likely to act on impulse and get a dog without thinking it through.
I'd disagree with that. If a breeder was really interested in getting the best home possible, she'd be interviewing and homechecking and doing a bit of legwork, not simply trying to make even more money from the dog, and she may be preventing herself finding a good home by disqualifying one that couldn't pay out a large lump sum.
I understand where you're coming from but I wouldn't buy any dog or puppy from a breeder who was in it to make money anyway. Pippa and Barney came from kennels who only breed when they want a puppy themselves to show and I doubt very much they make any profit from their dogs once health tests, vet checks, vaccinations, microchips, worming, food, stud fees etc are taken into account plus lost working days. Pippa's breeder last litter produced just one dog by Caesarian
I think homechecking is a bit much to expect but certainly a breeder that didn't interview me thoroughly would ring alarm bells and, again, I wouldn't be buying the dog.
If someone can't afford to pay for the dog in the first place, I would be wondering how they would cope with the ongoing costs of insurance, food, equipment etc. If they had put thought into getting a dog, they should have had time to save up the purchase price.