[I warned you I could be shameless about promoting this book of mine . . .]

Maybe everyone already knows this, but it was news to me: the price that Amazon charges for individual books fluctuates (rather widely) from day-to-day. For instance, (and I assume this is generally the case), I've noticed that my book, which lists for $27.95, has been priced as low as $18.45, and as high as $22.75. That's a pretty big swing, percentage-wise.

There are a couple of interesting things about this. It's a very risky strategy, it seems to me. Having the ability to instantly recalculate the price charged for goods can be very efficient, of course, in allowing a merchant to respond to fluctuating changes in demand and fluctuating price points. On the other hand, it is a strategy that can only work well when it's not widely known that it is taking place. It's the opposite, if you will, of those "price guarantees" that many merchants offer -- consumers hate feeling like they've overpaid for goods (even if the dollar amount is relatively small, nobody likes the feeling of having been "stiffed"), and if they are reassured ex ante that they are protected against that risk they will be more likely to part with their money. Conversely, the knowledge that the price might drop at any moment gives them the incentive to defer their purchase -- perhaps indefinitely.

Have I blown their cover? Or was this in the category of common-knowledge factoids that somehow I had just missed picking up?

[And please note -- I am not unaware of the cruel irony that, if I'm right that this isn't widely known, this posting itself might have the perverse effect of reducing everyone's incentive to buy my book by making it more widely known (and thereby giving all you potential purchasers the incentive to defer your purchase . . .). Probably not the greatest marketing strategy, for me -- but chalk this one up to my naive Jeffersonian belief that, in the final analysis, more information is always better than less. Plus, what's a few bucks among friends?]