I agree with rudy too, If your going to buy an old car, find one well maintained with lots of records, paying a premium for that is well worth it in my eyes.
Also my car has 487,000kms on it. mileage doesnt say to much about it. My floors are mint, because the PO took care of the car.
p.s some places to look for rust is, license plate lights, under fuse box up front, rockers( mainly by the fender bottoms) and of course the battery box in the rear.