Could you maybe ask her is she is in contact with anyone that has bought one of her puppies from previous litters (of the same parents), that you may able to talk with? That certainly is no guarentee but it shows that she's not ashamed of her pups. Of course keeping them outside is not the ideal thing for socializing puppies, but unfortunatly some breeders do.
The price isn't too high, if it was any higher I would think that she is just in it for the money. Just because she's been breeding for 20 years doesn't mean a whole lot. But if your comfortable with her and the puppies, there isn't any reason why you shouldn't buy. Are you just buying for a pet or do you have other ideas, (showing?) Are they AKC? There is a suspension list you could check to see if she is on it or not. Let us know if you decide to get her/him...