Excellent project and write-up from Msbirfday on Instructables.

Amazon’s prices change constantly. If you leave items in your shopping cart for longer than a few hours, you’ll likely get alerted about minute fluctuations – $0.10 here, $2.04 there. Amazon and its merchants are obviously using some form of algorithmic pricing to squeeze the last penny out of the market.

That’s all to be expected (late capitalism and all that). But what happens if things go awry? In 2011, a pricing war broke out between two competing algorithms. The result: a book on the lifecycle of houseflies (out of print, but not particularly rare) skyrocketed to a price of $23.6 million.

Amazon’s recent acquisition of Whole Foods Market made us wonder: what’s stopping dynamic pricing from stepping into the physical world of retail? What if the prices in a supermarket were just as flexible as those online?

So, in this Instructable, we’ll be building a dynamic price display with an Arduino and a small LCD. We’ll also briefly talk about disguising and installing it in a store.

(And, if you’re interested, this Chrome plugin can show you the pricing history of any item on Amazon over the last 120 days.)

Read more.