Okay, if this is all hypothetical...
If I were ever to breed a mare I owned, it would be for the sake of being able to keep the foal. So, even if she were unregistered, I would find a stud that has conformation to compliment hers, and make the proper arrangements. I would look for a reg'd stallion, so the foal would atleast be 'half registered' with some breed association. That way if I ever did have to sell the baby, he would be a bit more marketable.
I have baby experience, so that would not be the 'reason' I would breed.
If given the choice, I would rather buy, than breed, because of the risks that pregnancy can carry with it...of course, when you buy a foal, you may not know how he will turn out, so there are 'risks' there too.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."