Ah the 530. Good call, the 525i feels slightly underpowered in the e34. That said... Heres some stuff to digest, and some stuff you'll want to look for on the car before you buy. 6500 is not a bad price assuming the car is in perfect working order.
The greatest site for e34 knowledge on the planet. If it's a common repair, it's listed here: BMW E34 5 series Website
As for stuff to look for on the car that may need to be replace, at 100k+ new shocks in the front is pretty much a standard thing. Fan clutches on these cars are also very common. Check that. Here's the list of what will break: BMW E34 Website
If the dashboard at any time durring your test drive shows "TRANS PROGRAM".... Run. Run far away. Make sure you shut the car off several times durring the test drive. The message will only pop up upon starting the car. It's not really a hard glitch to fix, but you will spend weeks and weeks chasing down the problem.
Good luck! 6500 is not a bad price at all for that car, but make sure it's not going to need a grand in front suspension work. A fan clutch should knock about 200 off your price. Just look at the list and check the things off if you run into them.