How much motivation does she have, and what is her tendency to stick with it? Also, what kind of riding will she do? In my wife's case, she will never push herself too hard, never do long distances, never hit past 10mph, never ride anything with hills, and will jump around on what 'exercise' of choice she is doing. If like mine, then good enough not to have issues (which would stop her from riding), spend a moderate amount ($500 or less) and not too much of a 'racing' type. Would need to know more about her before could make any kind of recommendation other than nothing from a box store.