For people interested in buying a Leaf three or four years (you can get one for $12,000 or less) old with high mileage, the following is basically the only cost you need to add to the purchase to get as much mileage out of it as a brand new one.
Source: Leaf Forum: http://www.mynissanleaf.com/viewtopic.php?t=22319/Note: Wipers, tires, and possibly wheel bearing changes (after 125,000 miles) are the only other maintenance issues to consider.