Aside from the higher cost of just about everything out here... I think part of the reason for the increased cost is that driving here is generally the easiest on cars out of anywhere in the country. On the coast we hardly get much of a winter, and in some ways they end up in even better condition than cars from the southwest because they don't get blasted in the sun and sand. Less salt, less cold weather idling and everything else...
I think you'd be hard pressed to find anything older than '90 with less than 2-300k on it. I've seen some nicer looking ads than my '81 every now and then, but assuming they're in the same mechanical shape - they're all stock and don't have the nice interior, wheels, and all the cosmetic updates mine has... and most of the nicer desirable ones are upwards of $5k.
I'd love a nice looking late 80's 300SDL with the black leather interior like I've got and some nice modern wheels. Add on a few performance bolt-on's and I'm in business!
1981 300SD - 283,000 KM's at purchase, 325k+ now. 16" CLK wheels, w126 gen II cosmetic upgrades, late w126 leather interior.
1983 300SD - 550,000+ KM's. first MB, $900 year long adventure.
1999 Ford E450 7.3L Power Stroke turbodiesel 27ft 20 passenger bus - 600,000 KM's. band touring machine.