Yea but the seller has to agree to the sale(I think thats what you meant but I'm not sure). An advertisement is simply an offer to negotiate, not an offer to contract. This is why getboards does not need to follow through with the deal, but as SpinninMacinnon said Tramdock would have to sell the pants because they completed a contract to sell with those that purchased them.
That being said, to my knowledge a seller is not obligated to make good on an honest mistake in only advertisment as long as not formal contract offer has been made and accepted, but if the 'mistake' was intentional then it could be price-baiting(I think is the term), and that is not legal.
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