You may have a tough time making this NOT one-sided, because all the the stuff you’re going to read will be against buying from pet stores – which get their animals from “puppy mills” that allegedly breed them in very poor conditions solely for sale in pet stores, vs. animal shelters that rescue dogs or breeders that produce show dogs. PETCO is an example of a pet store that refuses to sell animals, I believe, in support of people getting them from shelters. So the problem with “some people who believe it is alright to buy from the petstore” will be someone who either owns a pet store or a general member of the public who is uneducated about the subject and not qualified to be quoted in your paper. If you could research and find a supplier of these animals where conditions are OK and support that side THAT way it would make a balanced paper, but that’s a lot of legwork, it seems.

Not sure if your topic is truly clear. Are you meaning whether people should “Adopt” or “Buy” their pet which is what I take from your title. Or are you meaning whether people should get their pet from Breeders, rescue groups/SPCA, versus a pet store. If the later, I would recommend a title more like:

” Obtaining Your Next Pet: Pet Stores, Breeders or Humane Society”. The topic has a lot of merit as you can discuss the pet population, efforts of celebrities like Bob Barker from “The Price is Right” to get folks to “fix” their pets. The issues with many of the pet stores in the 70s and 80s and why most stores no longer sell pets. Why most places now facilitate the adoption process from humane societies.