I took to long to edit that last post.
I wanted to add that if the seller doesn't care if the new owner breeds her, to ask her price, and sell her for what ever she wanted. But again, if she were mine, and I was taking such a loss on her, I would make stipulations the other lady had to follow.
I would ask, say, 5k. If the lady couldn't afford it, I would drop the price to what she could agree on, but not sell her with papers. If the buyer wants to breed a colt to keep for herself, fine, she can have an unregistered colt, and if she wanted him registered, to contact me, I would give her information to the stallion owner, and registration could be arranged, but for a fee. But based on the fact you said that the buyer doesn't ride, she probably wouldn't care if the horse had papers or not.
This is the way we do our border collie pups, to prevent irresponsible breeding and to preserve the quality of our bloodlines. Such care should be taken with a breed such as the Friesian.