Another thing to bear in mind is costs.... you mentioned that you thought pet store prices were too high, but if your chinchilla ever need veterinary treatment costs could escalate very quickly. I had a chinchilla who sadly died of malocclusion, but treatment wasn't cheap and even then it couldn't save him.
Chinchillas are seen as exotics in most practices (they are here in the UK anyway!) so they often charge more money to examine them etc. Chin cages are also quite expensive and you have to pay out for wood chews, high quality pellets, hay etc regularly that can soon add up too. I have three chinchillas, not that many but husbandry costs can soon add up even then! I spent about £100 last month on chew toys, hay, pellets, grasses and things for them. Ok, I hope that will last a little while.......
.... but even so... you get the idea!
They are wonderful critters though. If you can help out at the rescue I think you would find it really rewarding, you'd have the pleasure without the expense too!
I hope you don't mind me mentioning this, it's just another factor you may want to consider that's all.
There was a sad incident on a chin forum I go on in the Uk recently, where a dog got into a chin room and killed two of the chinchillas. I think you'd need to be sure you could have the chins in a room that the dog cannot access for the chins to be truly safe. If you can't ensure that, I don't think it would work. Chins need to have free range time etc and if it wouldn't be safe, it would be hard. They can be *very* destructive too, so any room you let them out in would also need to be chinchilla proof! (Is there such a thing?) Ours have eaten walls, skirting boards etc.
Hope this helps you in your decision. Maybe research them as a future possibility? That's what I did before I got my three. I must post pics at some point - I didn't have them last time I came on PT. They are lovely chins, I wouldn't be without them now!