Jeez, cars are expensive where you live -- €7,300 could get you four R50s where I live, LOL.
Anyway, the car looks like it’s been taken care of. I’m not too sure about rust issues since it doesn’t snow or rain much where I live, so maybe someone else can give better insight on that.
What I would look out for is whether it still has the original engine. A known problem with the R50 is the butterfly valve screws on the power valves they can come loose, fall into the engine, and completely destroy it (happened to me… RIP). You can read more about that issue here:
https://forums.nicoclub.com/threadlocker-on-power-valve-screws-pics-t304263.html
Also, check for:
White smoke from the exhaust
Whether the transmission shifts through all 4 gears
Functionality of the 4x4 system
General wear and tear: CV boots, bushings, bearings, etc.
Any power steering leaks - listen for pump noise when turning the wheel, and check if there’s any ATF fluid under or on the car
Check how the car idles and if it holds temp
Hope that helps