i think age of them helps too. in theory, a newer boat (same model) should be higher value. between those years there wasn't much difference from a 97 to an 03 or 04, so why not save a few thousand and go with a well kept 97 versus a well kept 02?
therefore, less expensive boat with same performance is more highly sought after.
on another note with boat graphics, it's unfortunate it's rarely done correctly from the factory. all brands. the neon green or orange stuff, metalflake, i just don't understand that. especially when you're forking over 6 figures plus for some of these rides. a guy drops 135k on a new G, and it looks like a flippin circus? maybe i'm the outcast on that but the timeless classic looks/graphics are the ones that hold value and have better appeal.
my buddy restored his 77 nautique. all white with simple red "nautique" on the side. that's a home run.