Solberg had quite limited funds but it seems that Kubica has a lot of funds.

So, it is actually win-win situation for both sides. He still buys all the parts from M-Sport and they get their money, I belive they get even more money as they are selling new parts for him.

Kubica pays a bit more but this time he can be sure that he gets all new parts. If he has enough funds then he can make sure he changes everything as often as needed.
As far as his name is so big in Poland, he can afford it.