The problem with any kind of "sale" event is that you teach people to wait. That's no good for business. You wanna have consistent movement. Once in a great while is ok - you may end up with a lotta stuff in stock that you really wanna get rid of before the tax man cometh, for a variety of reasons. But, telling people that you're not sure of the value of your goods is invariably bad, and that's the impression you give when you whimsically fluctuate prices.