Worth the Money/Work?

When in comparison to a flat window, Bay windows can definately increase a home's charm. It reaches out to capture more light and views from three angles, and the seat provides extra space for plants or a sunny sitting spot to relax. But does adding a bay window increase the home's value enough when a homeowner is preparing to list? And upgrading to a bay window will most likely require a professional, which costs the homeowner money. So is this upgrade work the money/work when getting ready to list? Any thoughts on this?