I have strong doubts about getting anywhere in the vicinity of $5K per year on a boat of anywhere near this level of sophistication (all those systems!!!!!!!!!!!!!!!!!!!) and age. A ski boat can easily cost you that much.
My
rule of thumb that's been pretty accurate for decades on my boats is expect something like 10% of
new boat cost per year for maintenance. Its not the
hull and
deck (those are the cheapest
parts to build and maintain for any boat I'd ever consider), its the SYSTEMS that cost the big bucks. And all that stuff (a) dissolves in
salt water so nearly everything in a boat needs to be replaced every decade or sooner, (b)
parts are expensive, (c) removing, repairing, replacing, and even maintaining often takes dramatically longer than the initial
installation.
To properly scare yourself away from a complex vessel: get the complete list of every part that has gone into the boat: every light fixture,
electrical panel,
pump, hose,
motor, filter, ... This list will be many pages long. Consider the cost of each of these: the
price of the part to replace, the amount of work to get at the part to be replaced, the amount of
electrical and physical interfaces that will be required to be futzed with in order to replace the old and out of production model X with the new and improved and a little different model Y, all the tools and fasteners and glue needed to connect the thing into the system, the time to confirm you actually fixed the problem, and the expectation that putting the boat together after the
repair will result in new rattles and
leaks that cause some other device to soon fail.
At a
boat show, I asked the
broker how one would fix the pressure
water pump that I could tell was buried far under accomdations and structure. He said you would just sell the boat.