I just re-read this. You are planning on going used, right? New RX models are $10k+.
What are you looking to get out of it? I would never buy a 3 seater. Sure you can legally tube\board\ski behind it… But they are just too big. Just play behind a two seater and watch out for the aqua-cops.
No clue on service on the new models. Mine is too easy.
EDIT_ I miss the old-old XPs. They were so fucking light and small.