FYI my wife and I paid $7750 for a '93 740iL with 113,xxx miles on it last August, so the price is close to what we paid. Even more important is that it's worth every penny! My wife and I both LOVE this car. It drives and feels like no other. We've concluded they don't call 'em "The Ultimate Driving Machine" for nothin''. This car's engine was probably replaced due to the infamous "Nikasil Problem". BMW may have replaced it with another Nikasil engine but most of the "danger" is past IMHO. And yes, many owners report 200,000-300,000 miles without major overhaul.
However, they are complex cars and things do go wrong and fixing those things can cost quite a lot more than on, say, a Chevy. I've got pretty good tools and pretty good skills so I can do a lot myself. If I had to depend on the dealer to fix everything, I couldn't afford it. This forum and
www.roadfly.org help a LOT, a LOT, a LOT.
Here's some things that likely need to be done to a 740 at the age of the car you're looking at in no particular order:
1) Bushings on the Upper Control Arm (also known as the Thrust Arms) probably need to be changed. The bushings don't cost much but they are a PITA to change. Replace them if the car shakes when braking or if the tires start to "cup" (will look like someone took a spoon to the edge).
2) The two oxygen sensors wear out at 60,000 miles so this car is probably on its 2nd set. Symptoms: rough idle, Check Engine light on sometimes. Advice: Use the (user unfriendly) Bosch website to find the right part number, then use Ebay to buy the right part number, borrow special tool from auto parts store and do the work yourself. Or, buy the parts on Ebay and find someone to install them.
3) The driveshafts often need to be replaced at about this milage. Symptoms: A bit of vibration during acceleration, OK at cruise. Buy a rebuilt shaft and have someone install it. (This is hard to do at home because you have to drop a large portion of the exhaust.)
4) Change the transmission fluid. Originally the makers of the transmissions, ZF Industries in Germany, claimed they were a "lifetime" fill. Now they say the fluid should be changed at 100,000 miles (See recent post for email exchanges). The fluid for these cars is very expensive so it will cost several hundred dollars to have it changed but it should be done. Again, you can find an internet source like Jaggi Transmissions and pay someone to do the (messy) work.
Hope this helps. I've done all of these things so we've probably got about $10,000 invested in this car. But again, it's worth every penny.
Good luck.