VW's service intervals are at 15,000 KMs. Check the service record with the VW dealer before you buy the car. Reasons:
a) Of course water pump expense.
b) Many rubber parts like the hose connecting the radiator & the engine, and many other rubber hoses from the engine would have degraded over time.
c) The gasket of the engine may need replacement if the engine has been overheating for quite some time now.
d) Check the condition of break pads, as well as the disk drum itself. If it was not replaced at about 150K, that will need replacement.
Basically, if you buy this car, you can LEARN a lot about VWs car mechanism before you offload it to someone else. But if your need for this car is temporary, like no more than 1 year, then go for it, and just change the water pump.