Buy one with a straight chassis (look underneath), minimal rust and good interior. Ignore kms as it would be wound back. Engine/gearbox will be getting tired by then. $15k for a decent one + spare money for rebuild/replacement.
Mine has crushed jack points, some rough paint and dings/dents thanks to retards in car parks. If I didn't check underneath (didn't really care as long as it was straight), it would have sold.
A legit 50k km car will, by then, easily cost $25k+ and will be hard to find. You'll probably have to look at AUDM ones with more than double the price tag.
People want immac GT-R's for $15k. What do you expect from a 20 year old Japanese supercar which has been imported and changed hands a few times?