Need advice buying a car long distance

Check the oil pressure, after the engine is warmed up. I made the mistake of not checking it. I bought the car, and trailered it home - 4 hours. The next day I drove it about 30 miles, and checked the oil pressure. It was 5 at idle, and aprox 8 at 60 MPH. I drained the oil, and found metal on the magnet that was on the oil plug. Also, the bottom of the catch pan was deeply coated with Magnetic goo. -- The engine didn't perform as it should have. Bottom line, the cam was going flat, and other problems. -- Pulled the engine - sold it, and on to a BluePrint Engine. -- A costly error, on My part. Of course The Seller "didn't lie, or didn't push anything, on to Me". He just left that issue unsaid.