Considering the real estate means check the space on your desktop. The available real estate will probably limit the types of scanner you should consider. Handhelds are usually the smallest scanners and are great for small areas such as magazine or newspaper articles. Flatbed scanners are the all around most versatile since you can lift the lid and scan an entire book or other three dimensional item. Sheet fed scanners have a document or sheet feed device.
Film scanners are probably the best way to copy a negative.
Costs vary tremendously. You get what you pay for. Considering the cost you should look at the software bundled with the scanner. A scanner allows you to get lots of information in the computer. In the computer your photo enhancement software determines what you can repair and change.