I think there are some misguided views around.
Mags are about the weakest link on an engine. Overhauling them at 500hrs is a desirable thing. Just make sure it is not done by a cowboy.
Overhauling a prop at 6 years (which it sounds like this is) is perfectly reasonable too. Nobody knows the internal condition by looking at the outside of the hub. Anyway, based on
previous postings by its owner here and elsewhere, that 6 year prop has done about 1800 hours, not 700 hours, so needs looking at. Again, make sure it is not done by a cowboy (like that well known firm which got shut down for forging a load of prop overhaul documents).
The static lines are probably a waste of time but they cannot cost that much... Changing the seat belts is definitely a waste of time if they look brand new, but the mountings need checking for corrosion (should be done annually).
The vac pump WILL go one day; probably before 1000hrs. Changing it at 500hrs is reasonable. That's about 50p/hour on the engine fund.
One can buy all these parts mail order from the USA, at good prices e.g.
here and
here.
What is legally required is another matter. It is a bit complicated but I gather that only items listed in the Airworthiness section of the MM are mandatory; the rest are optional under Part 91. Overall, I have not found a significant saving in regular maintenance costs from being on the N-reg. The EASA moves do put costs up but the cost of doing the various small items is not that much. It is more irritation to take apart stuff for no good reason, than anything else, and this extra stuff results in the aircraft ending up in worse condition because of the monkey spanner people dismantling everything every year.