Thanks a lot Dub!! I have the price list of the importer in 1990, and this one was sold at more or less the same price of a Les Paul Custom, so I guess you are right with your estimation, even if market rules are sometimes strange!
Anyway both the Floyd Rose branded Gibson and the Steinberger lever (to play seated) are original, at that time Gibson was the owner of Steinberger, that's what I learnt.
thanks again and have a nice day!
Andrea