Except economy of scale should have lowered that cost dramatically. The Steam of today is incredibly profitable compared to the Steam of 1994, that means costs have gone down, but their commissions haven't followed, and this is why others want their own store. If their commissions were fair, it wouldn't make business sense to compete with them.

Planting and processing my own wheat for bread would be very resource-intensive, that doesn't mean commercial bread is a luxury article.