Hi Luann,
Welcome to the forums!! Chinchillas are wonderful pets and watching the miracle of birth is wonderful when it all goes OK. One thing you won't have to worry about is ending up with 50 babies. A female usually only has 1-2 babies a year (although its not uncommon to have 3-4) and if you give them the rest they need between deliveries it should come to about 1 litter the first year, 2 the next, and one the next. So one average one female could give you about 7 babies in 3 years. Some more, some less.
Here are a few articles I would recommend:
Chinchilla Pregnancy 101 = it talks about chinchilla reproduction, breeding, pregnancy and delivery
http://www.huggablepets.com/huggablepets/preg.shtml
Understanding Quality Chinchillas- Don't miss this one. It talks about good quality and how to pair them. Even if you are never going to show and will only sell as pets its your responsibility to be sure that every baby you produce is the best it can be. We should all be striving to improve the animals we love by being very careful about the pairs we put together.
http://www.huggablepets.com/huggablepets/fur.shtmlOne big dilemma with breeding in pairs is that the female can get pregnant the day she delivers her babies. This is bad because if she is pregnant and trying to nurse her babies it can be very hard on her. This means that you will need to remove the male before she has her babies. This has its own set of problems because the male can go into depression when he is taken out. You have to watch him very closely because sometimes he will stop eatting and drinking and can die.
You will also need a very good vet on call that will see expotics, and a complete first aid kit in case something goes wrong. I would suggest reading over the breeder sections of the forum because we have had a lot of topics on problems with girls needing c-sections, mothers dieing after birth, having to handfeed the kits, etc. You should have some plans for what to do if things go bad. If you are prepaired it won't be as scary when the time comes.
I realize that these last posts from me and Jo Ann don't sound very optimistic. Please don't think that we are trying to talk you out of breeding. We both understand the love of being a chinchilla breeder. We just want to help you know what to expect. We have seen people get sold animals with all of these wonderful promises and sometimes people tell you whatever you want to hear just to make a sale. (Not to say that is what happened to you...) We just want you to be prepaired for what is to come.
If you don't mind huge vet bills, staying up all night to feed babies, and always paying way more out than you will ever make on your chinchillas WELCOME TO THE CLUB!!!