I am not familiar with Madam Alexander dolls at all. But you might want to get in touch with The people a the Denver Doll Emporium. The owner has a deal of knowledge pertaining to antique dolls. Even if she doesn't have the information she may be able to help you find someone who does. Or find a doll store in your area. Worse comes to worse call someone who deals in estate or antiques toys. They can give you a great idea of their worth.
Hope this helps! Good luck.