I really think the only size women's bike that will work is a 42cm. The girl is small for her age and only 4'5". I found a 42cm on Nashbar on sale for $300, but it's still going to be a bit too big for probably a year as is for sure bottom of the barrel specs. Otherwise I'd like a Trek KDR 1000 (not made since '08) or a felt f24 (haven't found one for under $550) that were specifically made for kids.