With the pending sales success of the Model 3, I predict a shortage of NEMA 14-50 outlets. When the Model 3 is released, there will be 100's of thousands of people buying these outlets for their home-charging. I have to assume the manufacturers of these outlets aren't preparing for this but they should. So, at less than $10, it might not be a bad idea to buy the outlet now so you'll have it when the time comes because who knows how bad the shortage might be. And, even if I'm wrong, no harm in spending $10 now instead of later in my opinion.