I would not sink any money into a car with 260k miles on it. You can buy a Benz with 1/3 the miles of that car for about the same amount of money you would put into fixing the big things you mention (ac overhaul, struts, etc.). I see late 80s/early 90s 190E/300E in good shape with 80-120k miles on them all the time for $4-5k asking prices (which you could probably get for $3-4k; (they will probably need $1k of work to fix everything broken on them, but you would still have a car with reasonable miles with a reasonable life expectancy).

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car