You wouldn't think it would be anymore expensive, the cost is already ridiculous for 300winThe biggest obstacle I have to buying one is price. I'm not going to pay $5-10 more per box/20 just to get a shorter bolt motion.
I think the opposite is true. No one is buying the WSM's, which is why the shelves are so full of them. I see a lot of rifles in WSM calibers being clearanced at the gun shops.