When there is a supply constraint, SIM free versions aren't usually offered from Apple for a few to several weeks after the initial release. It looks like Apple has done a good job with the 8/8+ supply for initial release, but from all reports, X will be supply constrained for a while after the initial release. Besides, the X pre-orders don't even open till Oct 27. Your best bet to get it "soon" is to try to order one through a carrier when orders open, but I'd suspect they'd only sell them with a service contract in the early days.