4k on an e38 750 and you've overpaid! Unless it's low mileage in a1 condition.
They are rare tho, so finding a good one could be hard, but no one wants them that much so not worth much.
swb ones like mine seem rare compared to th L versions. but command no premium in price.
think if you had to pay for repairs they could financially ruin you. ( water pump failed on mine = £600 in parts! diy )
but cost aside its my runabout and driving a V12 daily never fails to amuse. 12mpg is the average, so even with cheep fuel, it might not be the car for you? I do less than 5k a year and 1K of that was in my economical 400hp sapphire