Is buying a BMW with over 150,000 miles on it bad?
I've found a 2007 BMW 530i 5 series with 150,000 miles on
it for $6,000 and was wounding if it's worth it and/or good?
Not a good choice. If you have $10K - $15K in waiting for repairs and you don't mind parting with it then buy it. These cars are made of as much plastic as possible and are crazy expensive to fix. They even make gears in the transmission and actuator out of plastic. You are considering a money pit in an old BMW.
Get a 2007 Lexus ES330 for the same price and 97% better reliability. What is a fast car when it won't move because the plastic gears are stripped?