I'd say good luck finding a well taken care of model that will get to 300k-miles without you getting nickle and dimmed to death. Love the cars but they just aren't going to last that long IMO without some cost. There is a reason they are cheap, EVERYTHING starts at $1k and goes up at the dealer. Ya, you can do it all yourself and save a TON but that's why people dump them (same with the S-class, 7-series, etc.). Not to mention people want the latest and greatest so when the new one hits the street, the old ones aren't desired by the people that can buy a new one every year.
If you can find one for $10k and under that's CLEAN go for it, but I think you'll spend way more than that over the few years you own it. I'd buy something that costs a little more but will be newer, less miles, etc..