If they still support it, they may be able to give you a copy of the media as long as you have the license for SQL. I think we managed to do that when 6.0 was replaced by 6.5 for a short time.
Also, it's possible that the app may run on 2000 if you set the DB Compatibility mode to 65. (I realize that's different than being supported.)
Our biggest issue with a 6.5 app we'd developed many moons ago was that it required a case-sensitive sort-order (default in 6.x). That needed to be set specifically when creating the database for 7+ if it was going to run successfully.
-Pete