I think I may go a bit off topic here but..
I honestly don't mind where I (not entirely mine, but our cats are one big family) get my babies. Be it petshops or from shelters.
We - my brothers and I - actually have bought 1 (Belle) kitten from a petshop, 2 mix-persian (Elvee & Teddy) from mudah.com, 2 mix-bengal (Bonnie & Clyde) from whom I suppose is a backyard breeder and last but not least, our 6 DSH cats we've picked up from the streets and adopted.
Most of the cats bought were from 'bad' places.
#1 The petshop I bought Belle from kept her in a very small cage and every other kittens that they sold. Even the large adult Persians were kept in the small RM50 cage. :/
#2 My brother bough Bonnie first. He didn't know she had a flu and fungus on her skin only until 2 days later. We called the breeder to complain and she said that Clyde was suffering from the same thing as well. My brother asked whether there would be any compensation if anything were to happen to Bonnie. The breeder said yes. We took the very best care of her about 1 week and a half. Then she got all better. My brother insisted on buying Clyde eventhough he knew Clyde was sick before. After we took Clyde home, he was delirious. He'd hiss and spat at anybody even Bonnie, but he never had the guts to bite anyone. (It could be that the seller neglected him or Clyde is really like that) Well, I don't know what happened but a couple of days later, I saw Clyde cuddling with my brother purring and he still does that until today. He also gets along with Bonnie.
I personally think that not only does the animals from shelters need rescuing, so does the animals sold in petshops - not that I support what they're doing but I know that we can give them a better life here with us.
Note: We all still live with our parents and our house and it's backyard is pretty big. So don't worry about overcrowding. xD