The one I bought was off ebay. It was from auto tops direct. Here is their website:
Porsche Boxster Convertible Tops
Looking on ebay, this is the top I bought, the german A5 cloth:
Porsche Boxster Convertible Top Black German A5 Cloth Plastic Window | eBay
It was of equal quality of the original top that I took off the car and overall I am happy with it. I do wonder at times if I should have done the glass window instead of plastic, and I probably should have, but if I have the car that long then maybe next time I'll do the glass option.