If you can be sure of the history/condition, a 190 will last forever.
I remember LJK Setright (famous motoring writer) lists the 190E 2.6 as one of his top 10 best cars ever created. They age better than almost any other car too, so are still awesome cars today.
Just ask the C-class owners who've upgraded from 190Es. Many of them regret it..
Simple enough to work on (but not that basic) too. Mercedes automatics aren't completely last-a-lifetime rock solid, but they're not a 'weak point' either, especially as they drive better than almost any other autoboxes around.
From my experience of 'domestic' US cars, you are in for a good time if this is your first Mercedes!
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black