imademymark sorry for the late response, but heres a more refined option, which im posting out of the curiousity of how other head-fier's would respond to each option, if given such an option (the first is more amazon friendly, the second more consumer friendly) -
Consumer puts 50% down of a future purchase, so maybe i want the HD800 for 1000 bucks. I drop 500 on them initially, and then once the price drops that low or lower, amazon bills the consumer for that price, and ships the HD800, if, after a year, the price never drops low enough, the consumer loses their money. Maybe shorten the time span for a lower percentage, so 50% = a year, 10% = 1/5th of a year, etc. etc. allowing ballsier consumers to gamble a bit so that if they feel confident the product will become affordable, they can get a steal, if they go too low, they get screwed, if they go too high (betting 1200 for the HD800) and the price drops from higher than their bid to drastically lower all at once, they end up paying more than they need to.
Another option, they could plot where slumps will be, and say perhaps there are no HD800 purchased in september. They set the price down to lose about 100 bucks per purchase. People phone in to pencil their names in with a down payment of 33%. The first person gets the lowest price, and the more people call in, the higher the rate gets, until its on level with the next highest month.