When do you call it quits?

[newbenzmom]

First I would like to say, I love my car - its a 95 C-280. I have had it since Feb of this year. Its got miles 275,000. Engine sounds fine. but we have a few things that will need repair>
Condensor has a hole in it so -No a/c. Repair will be $460.00
Lower control arm bushings need to be replaced.
Flex discs also look scary
a small oil leak
needs a window regulator for passenger window
and a small coolant leak was detected yesterday.

Is it worth it to put the money into this? How long can this car last.? Honest opinions please.