I was approached many times to sell to pet stores. At one point I was over crowded and did sell two kits to a pet store for resale. I was very uncomfortable about it because I am really big into educating my new owners on care. I had a long talk with the pet store owner about proper care and diet and she assured me she would continue with what I told her. A few days later I walked into the store unannounced and the chinchillas were being fed pet store "junk" feed, had the dust bath in the cage, and had all sorts of plastic accessories.
The bottom line is that most pet store items marketed for chinchillas are not safe for chinchillas. However, pet stores do not make their money in selling the pets, but in furnishing all of the items the pet needs. So when someone comes in and buys a chinchilla they won't say "I;m sorry I don't sell the best food" they will say here is a great bag of Chinchilla food filled with fruits and nuts your chinchilla will love! And here is a plastic wheel with spokes, and here is a plastic hiding house...." And several weeks later that poor chinchilla is sick from bad food and impacted from eating plastic and doesn't live out a full year.
But, with that said, perhaps you have a good store near you that does sell Mazuri brand feed and will give proper information. Pet stores usually buy pets for 1/2 of what they will sell them for. So if your store is going to sell a grey for $125 (way too much, in my opinion, but that is what they sell for around here) They would probably pay you about $60.
