water pump/thermostat brands

[mountainman]

Thinking of replacing water pump, thermostat and belt on 04 boxster. In checking prices, they are all over the board from very reasonable to utterly absurd (porsche brand from dealer ). Has anyone used brands other than porsche and what are your experiences. For instance, I have used gates belts for 40 years and they make a great product for other cars : are porsche belts really worth twice the price of a gates belt? The same with thermostats : there are german mfgs that sell them for half as much as porsche.
Also are there any feelings about metal versus plastic impellers on the pumps? thanks for any input.