If you can pick up a Nikon Coolscan 9000, that's the one to get. Its a seriously good scanner and will blow any flatbed scanner out of the water. They stopped making them a few years ago, but because they are so good, they retain their value quite well. I bought one in 2004 for £2.2k and sold it a month ago for £1.6k.
Keep your eye on Ebay as they sometimes pop there. Avoid the Coolscan 8000 as its painfully slow and has banding issues.