If you don't consider those aspects then the photos will offer little appeal to the buyers. If it were me, and an agent showed up with just a camera and a pop-up flash I would find another agent. This is not the place we want to go cheap. What you should expect is for the photographer to have an assortment of off camera lighting strobes, a tripod is a must if you want to have tack sharp images and assorted lenses. It's also not uncommon for me to shoot up to 200 photos for single 2000 square-foot house.