2004 MSX150 insane parts prices

Help! $520 for two pistons! $520 for an oil pump! $73 for a head gasket! Over $2,500 for parts alone (no labor included) to rebuild the engine in a machine that is only worth about $4,500 in pristine condition! I suspect the reason this machine has depreciated so dramatically is a history of engine problems, the difficulty of working on the engine and the price of parts. After one season the engine overheated, for no reason I have yet been able to determine, and scored the cylinder walls, pistons, rod bearings. I know another fellow locally who has an '04 MSX150 that did the same thing, and I bet there are a lot more of us out there. Based on the price quotes I have gotten from Polaris dealers and a so-called "discount" supplier, it would be prohibitively expensive to rebuild my MSX150 engine, and I will have to junk the machine. Does anybody know of a source for MSX150 parts at reasonable prices? Has there been a class action against Polaris over this machine? Is anyone else out there interested in starting one?