Sell? It's a collector! And tons-o-fun. How many kilometres? Original condition? you could try kijiji or craigslist and of course autotrader, but the first two are free and everyone who's looking for a bike cruises through those sites.
Hi: I too have GPZ900R 1984 just taken out of storage. I am thinking to sell. Any ideas where and how - in addition to normal channels e.g. this forum etc. thanks.../John