I can never agree with the idea that if you can't afford $X for a dog, you shouldn't own one, since my life was changed by a dog my parents could barely afford when I was a kid. She got fed, got netuered, and got taken to the vet when she was sick. It is not the way I take care of my dogs now, because I can afford to be Ms. Munchausen with their health and spoil my dogs rotten. But it was the only way we could afford a dog, and she was everything to me back then. And she had a very good life. If anything had happened to my dog, we couldn't have afforded to do anything much, but she was adored by a large family who was always around, talking to her, feeding her people food, walking her, letting her out into her yard, etc. And she had me to raise, a job she took very seriously. A job, companionship, food, water, and a place to run. What more does a dog really want?
One thing about price at shelters - when people can afford to buy a puppy from a breeder or a petstore but choose to go to a shelter, they probably are doing it because they're aware that there are more homeless pets than homes, and they may not expect there to be any obstacles or special cash cost to rescuing a dog from death. It's a reasonable expectation, and it really is the shelter's responsibility to educate them about why they charge so much. If the person truly can't afford the price, the shelter should try to find out more about their situation and help them either decide to wait until times are better to get a pet, or steer them toward a cheaper but good shelter.