The trick to avoiding this if you can’t build a rig yourself is to find a shop thats independent from any of the big corps and tell them very clearly you will not be using windows on it. They tend to hate dealing with microsoft too. There’s a shop in Toronto(PC Shop computers) I send friends to for this very reason. They’ll knock 100 bucks off a new machine and breathe a sigh of relief for the time and money you saved them.