Wonderful idea! Breeding gerbils is a great hobby, and something to enjoy! I am in the midst of breeding my two pair. You're right, buying them from the store isn't the same!
But you have to remember, once the mother gives birth (or during birth), the father will breed with her again! So if you are expecting one litter, think again. You have to be prepared.
So just read a little more about it, here is a great site. I printed this out:
http://www.agsgerbils.org/Gerbil_Car...k/breeding.php
www.agsgerbils.org