Also these guys up by Wausau, they do more new sales, but get used stuff in all the time as well.
http://www.machinetoolandequip.com/
With the economy down a bit many of the used dealers are desperate to get rid of stuff and are more willing to deal than they have been in the past. I got a used full auto bandsaw for my CNC shop from a dealer over in Detroit for cheap (even with shipping) a couple months ago.