A clever idea but I worry what happens to the people that miss out. They are either aware they've paid $2X (if you tell them) or they are aware that they've been "ripped off" (you are prepared to give it away for $0 so you must have at least 50% markup. Kind of like jewellery stores putting half price sales on $10-20k diamond rings). Either way you are associating negative feelings immediately and a sense of buyer's regret.

On a practical note, what stops them getting a refund and repurchasing until they get it for free.