my BMW dealer says that the cost of plastic are not yet validated but approximately the two big one sides are about 200+200 euros, the smaller ones i suppose about 150+150 and the beak about 150, so in total it is about 850 euros.
I don't think it is so high.
If you consider I find to sell my old ones for about 350 euros, the balance is 500 euros.
Now it's up to me to decide and i'm not yet sure, but of course if I need to add other plastic such as radiator cover or something else, the cost is not effective and a new bike is better.
anyway it is interesting the evaluation.