Hi Leslie,
What are you feeding them? Even with poor quality you shouldn't be able to feel your chinchilla's spine and ribs. He sounds very underweight. It could be that you need to feed him a higher quality feed to fatten him up a bit. Is he more hyper than the other one?
As for quality, a good quality chinchilla should have very thick fur that sticks straight out and doesn't lay down. The ideal fur would be so thick that if you were to blow into it you wouldn't be able to see your chinchilla's skin. When you stop blowing it should go right back into place so that you couldn't even see where you blew.
The body should be square. When you look at your chinchilla from above his hips should be as wide as his shoulders. He should look like his head was attached right to his shoulders with no or very little narrowing of his neck.
Breeding two small chinchillas together will give you even smaller babies. Breeding colors together instead of breeding a color to a standard will typically give you smaller, lesser quality chinchillas. (Breeding one mutation color to another could give you nice babies but those should always be bred back to a standard to get nice babies. If not the babies will continue to get poorer quality)
With that said, getting a poor quality chinchilla from a breeder doesn't make the breeder bad. Even the best chinchillas will occasionally have a dud. We as breeders just have to be sure the the majority of the babies from a pair are what we are looking for and make sure to sell the lesser quality chinchillas as pets. They are still just as loving even if they aren't always lookers.