I am not an expert on Biewers so keep that in mind with my response. The cute little doggie in the pics you posted just doesn't look like a Biewer to me. That doesn't mean she wouldn't be a fantastic pet, but you certainly don't want to purchase from someone who is not being honest.
It might help if you studied the Biewer standard - here are a couple of links:
Biewer Terrier Standard biewer standard - Yahoo! Image Search Results Your Biewer Resource - Biewer Standard