Well, shapiros, I would avoid a 750iL unless you are nuts about having a V-12. I thought about buying one before I got my 535i, and would have gladly taken a 735i or 735iL. 750iL's are so affordable for the $70-90K they used to cost that the idea is very alluring.
First of all, gas mileage is in the toilet, and with 93 oct. gas about $2.50 here in MD and higher elsewhere, I'm really glad I didn't get a 750. To its credit, the BMW V-12 itself is actually supposed to be a very strong, durable engine. If that car was well-maintained, 145K is not actually TOO bad, although I wouldn't pay more than $4,000-4,500, even if the car is in good shape.
The problem is with all the other systems and electronics in the car. In a lot of cases, there are TWO of many components (two catalytic converters, $2,500 each) where there is just one in ordinary cars. Parts will not be cheap, and I don't imagine labor will be either. 750's are supremely complex vehicles, and there is a lot that can go wrong. When it does, it's possible you may end up spending more than the car is worth to fix it.
I don't know how much you are looking to spend, but if it were me, I'd look at an '88-'92 735i/iL on a less than $5K budget. The E32 '93-'94 740's are nice but you have to make sure that the original Nikasil engine block has been replaced with an Alusil one per BMW's recall (all 1993-1995 740's and all 1994-1995 530's and 540's were affected). If I could spring $10K, I would try to get a '96+ 740i or 740iL with the newer 4.4L V-8. Those cars are much more contemporary as well.