I wouldn't say that I know it all by a LONG shot but I do know a lot of the Washburn Dime guitar history. IMO the Washburn USA's were the absolute best of the dimes and flat pound the dean in the GROUND!
If it is a 333 slime $600 is on the high side if it is a USA Dime 3 slime that is a STEAL!
Here was the one I had it was bought by a dealer from the floor of the 2000 NAMM show. SN