Yep Brian nailed it. I am playing both sides of the fence with this one. Anyone who knows W126's could probably pick out $3k-$5k worth of stuff my SD needs to bring it back into top shape. But it runs and drives fine, granted not everything works that great but it runs pretty darn good.
I have done nothing to it other then oil, fuel, and air filters. The only "repair" parts I have installed were a $9 tie rod end, $65 battery, $20 worth of heater hoses, a $15 fuel filter bolt, and a $10 t stat. So $120 worth of parts and thats about it for this driving season on that car. I'll change the oil one more time and thats it until next fall. Maybe next fall I'll throw on a set of front brake discs. Basicaly its a $500 car I am running into the ground over two winters and will dispose of after that. But I spend less then $200 a year maintaining it.
After doing this I see that if I spent a bit more say $500-$1000 a year I could keep it on the road all year round for at least the next 5 years. So you can drive them cheap, but don't kid yourself your running it into the ground.