Adventures in shopping continued: Amazon and daily pricing shifts

This is fascinating. I blogged previously on the dramatic fluctuations in Amazon and Amazon partner pricing for the very popular Canon Digital Rebel XT. I discovered then that if I put a variety of this item on my shopping cart, then 'deferred' purchase to "later", I could see the price changes as they occurred. Their were quite a few today -- similar to airline ticket price changes:

Please note that the price of Canon Digital Rebel XT 8MP Digital SLR Camera with EF-S 18-55mm f3.5-5.6 Lens (Silver) has decreased from $899.94 to $879.94 since you placed it in your Shopping Cart.

Please note that the price of Canon Digital Rebel XT 8MP Digital SLR Camera (Body Only - Silver) has increased from $838.94 to $854.99 since you placed it in your Shopping Cart.

Please note that the price of Canon 50mm f/1.8 II Camera Lens has increased from $74.94 to $75.99 since you placed it in your Shopping Cart.

Please note that the price of Canon Digital Rebel XT 8MP Digital SLR Camera (Body Only - Black) has decreased from $829.94 to $799.94 since you placed it in your Shopping Cart.

I'm sure someone has s written software that will check the deferred cart list items every 10 minutes, and execute a purchase based on the price fluctuations. Buying from Amazon.com these days seems to resemble buying shares on the NASDAQ. Inevitably the same sofware used to execute trading strategies will be used throughout the retail chain.

It's not just electronics by the way. The price of the Calvin and Hobbes compendium, a book, just jumped $10 on my shopping cart. I assume Amazon is adjusting costs in real-time based on sales, competitor pricing, customer profiles, the cost of gasoline, the futures market, and some randomness factor to measure the impact of different price points.

More complexity. More obscure costs. Where does it end?

PS. My "buy signal" for the next five days is something around $840 for the camera with the default lens.