Not sure that it will matter to most of you, and perhaps it shouldn't, but costco got those shoes on the black market. Very good chance that they are counterfeit.
I have worked in the outdoor/comfort footwear industry for 30 years, Sperry is one of our competitors. I can guarantee you that Sperry did not set Costco up as dealer, they either got the shoes through some back door dealings with an unscrupulous reseller or they are counterfeits. At that price, the counterfeit option is much, much more likely. My brands have to be constantly vigilant to keep our product out of Costco and Sam's, they try every trick possible to get any of our shoes that they can.
Just be careful. You're likely not getting what you think you are. It's your feet and your integrity. My advice is to spend the extra $50 and get them from a reputable footwear store or outfitter.