I recently got into photography, and there is a never ending list of things that you can get into.....lenses, flashes, grips, tri-pods, it never ends.
What does she take photos of? That will largely determine what type of lens to get, and how much to spend. I just picked this one up
http://www.dpreview.com/lensreviews/...p8_is_usm_c16/ and it's pretty much Canon's flagship lens for the hobbyist. Not the cheapest, but it's the closest thing to pro without the huge dollar attached to it.
Try the Camera Store on 11th if you're looking for camera stuff, they've been really helpful to me in the past.