You have to buy it all at once instead of a little at a time so the initial cost may be higher. You may have some contention issues. In some products, you can do these things. In others, you cannot. It may not be obvious which is the case, so check.
Images tend to take up a lot of room on the disk.
For this reason, you may want to consider more hard disk space or a removable format such as Zip, Jazz or Syquest disks. Remember, many images may not fit on a floppy. Frankly, you can never have too much disk space. Memory, too, can be an important factor. Working with images also tends to take a lot of computer memory or be very slow.