Hi, The links given you are good. Rehau is a very good product, particularly their Tritech system 60 mm system. However woodgrain on white is about 15 to 20% more expensive than standard white.
Having just read your question again you may find the price will go up further as I notice you want White on the outside and W/G on the inside which is not normally standard with most companies although they can do it. Normally W/G is on the outside and white inside.