I'm the sole IT guy at a small (but technically 'mid', I thought) company, but I've worked with much larger organizations, academia and government before. At no time have I ever encountered the buying of 'thousands' of servers a YEAR... What would be your idea of an 'Enterprise' or 'Large' company?

You're also forgetting about the inevitable markup these management places charge that all but negate any cost saving benefit from the lower prices.