Which plaster is the surcharge calculated for? Probably normal roughcast? Then the price is okay because there is significantly more effort involved in the application. And see how you imagine the broom finish, there are huge differences in its expression! I also believe that it could be too much in combination with the wood. I find both the broom finish look and the wood accents very good; you see them more and more in our region, but I have actually not seen them combined yet. Maybe because the overall appearance becomes very busy?