+1 Fit is everything if she's not comfortable she isn't going to enjoy being on the bike. Another issue is not to worry about standover height as much as top-tube length. Go through a few of the fit calculators and check out a few of your local shops. You might find a sora bike locally for a bit over your budget although it's not likely, it might be possible.

Also check out Performance, they do an additional 20% off every now and then +10% in performance points and you could get her something decent for a bit more than your budget if you're lucky.