Most guys on here pull the drives once a year to make sure seals, u-joints, and splines are functioning "properly".
I change my drive lube once a year or every 50 hours - last year coincidentally I put about 50 hours on it. I would probably change it more often but I RARELY run the boat more than about 3500 RPM and the majority of my 50 hours are spent idling.
General maintenance includes the greasing of the spline and U-joints, and the changing of the gear lube.
Regardless of whether you are handy or not - you can do it yourself.
I have bravos. Judging from the boats you seem to be looking at you should either have Bravo's or TRS drives....