The cost of annual/100 hourly maintenance varies.
I've had the same plane with the same maintenance organisation for eight years. It's a small GA organisation with very experienced staff that are experts with this type of plane.
Some years it costs over $20,000 (needed new top end kits, magnetos), other years it costs less than $2,000 and is done in a couple of days. Luck of the draw.
I think it's important to support local LAMEs and rarely question a bill. They need to make a buck to survive and be financially viable. It must be depressing for the owners of maintenance operations seeing owners trying to be cheap by removing panels etc themselves to save a couple of bucks.
The rate for a LAME at Moorabbin was $70 an hour last time I looked, and I can't see how they would make a buck at this kind of rate especially given the overheads. I can't imagine it would be any cheaper in the USA and I don't think the LAMEs would be any better.
Dick, how about you upload a copy of the quote to give an idea where the costs are being incurred?