The GPs are pretty good, and 150K isn't all that high mileage these days. Have the vehicle checked out well, if it checks out you are good to go. With basic maintanence the car will be good to go for a long time.
You also have to ask yourself, what do you expect from a $2000 car? If you are expecting the reliability of a new vehicle you are likely to be disappointed. Then again, I bought a 96 Neon for my wife earlier this winter for $90with 140K on it, the head in the trunk and a filthy interior. After rebuilding the head, putting it back together and a lot of quality time at the car wash, it is a nice car, it started up first try, and hasn't even hiccuped since. As a matter of fact this week I got a little surprise, the wife turned the AC on and it blows ice cold. Not bad for $90.