Sunroof installation ever done who?

Hi guys, wanted to put a sun roof in my passat. Was once from Interrese with the specs of ATU for a price information. The roof costs 102 euros, I find quite realistic. When asked what the installation costs, he says to me 175 euros. Must me laugh hard. Has someone ever built such a part into me? What to consider? Which manufacturer is recommended. This at ATU is from Webasto. Thanks already, Frank