Volvo parts cost an arm and a leg. However, they're widely and easily available, for engines ranging (I think) about two decades now. This costs a lot of money. When you design and build an engine, there's a lot of custom parts to make, with a variety of production lines to set up. Now to have a steady supply of spares available, you can produce a huge amount of extra parts and then tear down the production lines to free them up for the next engine model. Put all the extra parts you made into a warehouse and then supply them from there. When they run out, that's it, no more exhaust elbows for your engine. When some parts are not needed, because it turns out that part never fails in 20 years, you wasted a lot of money building up and storing stock that will never be needed. The other method is to keep the production lines and keep making parts on demand (or rather, in batches). You can supply parts for as long as you want, but you have to house, operate, train staff, etc. for a large variety of engine parts production. Either method costs a lot of money, which is a big part of why these stupid parts cost so much money. Another part is no doubt profit, and I'm sure there's a nice bit of that in the spare parts business, but not as much as many boat owners think.
Now "putting pressure" on Volvo is unlikely to impress them. The one thing that boat owners can do would be to say "I'm not buying anything with a Volvo in it". While some certainly do, that doesn't seem to be the case much, or production boat companies would long have switched to another supplier (they want to make profits too).
What we boat owners can do, is get a bit smarter about where and how we buy parts. Not all parts of a Volvo engine are actually made by Volvo, many of them are either standard parts, or custom parts by another company. If they're standard parts (like an alternator belt, oil or fuel filter), you can buy them from any car shop, just need to look up the right one. If they're custom parts (like my raw water impeller pump, which is made by Jabsco), they may be available from the supplier, but not always, or they may be used in other engines where they're available as spares for less money. The difficulty here is to find matching ones. This also plays a role in spare part prices by the way, as if a third party supplier stops making an item, Volvo will have to find another one or start producing it themselves.
And finally, not all Volvo Penta engines are actually designed by Volvo. For example, my MD22 was designed by Perkins. I know it's a Perkins Prima M60, so I can buy parts for that which are identical. Apart from the marinized bits (heat exchanger and cooling system). And there's a Haynes manual for it, because it was the engine for the Austin/Rover Montego 2.0 Diesel (which is better than the Volvo workshop manual in many ways, because it tells you which standard tool to use of "Volvo special single-purpose tool with part no. XYZ").
Lastly, there's the used parts and engines market. There are some parts available on eBay, and there are whole used engines there as well. I know at least one mariner who bought a used engine (a Yanmar in this case of the same model as his) and stripped it down for parts. This is of course only an option if you have a place to keep it all (or the patience to flog parts below original prices on eBay).
Also keep in mind, in some cases it may cost less to repair rather than replace, or even get a spare part made in a machine shop rather than buying it from Volvo.
So what we can do is share such information, e.g. which Volvo part numbers cross-reference to other manufacturers or where you got a part made or repaired. Hope this helps!
