Here's a questions to ask yourself, do I have the means to support the foal if something were to happen to my mom, does my mom support the idea of another horse to feed, what do I plan to do with the foal, do I have the experience or help to raise and train the foal.
In this economy there is no way to recoup the money you put in to breeding and feeding a foal, there is no profit in breeding right now it a loss.
But breeding your mare is your and your parents decision. Most people on this forum will tell you NO not a good idea if you looking for something in particular buy it don't try to bred it. Just because your mare and the stallion you choose has great bloodlines and conformation doesn't mean that you will get them from the foal there is no guarantees the foal will come out to be what you wanted or expected.