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arcadeLeon's right, any of the cheaper models will perform beyond what most of us here need for scanning cards or photos. The fancier models really compete with the specs you would see on things like drum scans and negative flatbed scanning, all services you should go to a pro graphic service bureau to handle.
A suggestion with scanning - skip the free software and use photoshop if you have it. Just install the TWAIN driver. It should still do an auto scan but you can change the dpi, or colors easier.