I've found myself in an interesting and illuminating loop lately. In February, I wrote an article offering some money-saving shopping tips. Good enough, right? Well, I quickly heard from some folks who offered me additional advice, especially about where to find great discounts and coupons online. So I then wrote about how to be a smart online shopper. And then -- you guessed it -- I heard from more folks. So here's my next installment, this time focused on ... (drumroll) reverse auctions.

With traditional auctions, such as you'll find at eBay (NASDAQ:EBAY), buyers bid on items, driving up the price until no one wants to bid anymore or the time runs out. With reverse auctions, an item's price starts out high, and then drops -- until someone buys it, ideally. This is similar to the "Dutch auction" concept, which Google (NASDAQ:GOOG) used for its IPO.

Here are a few sites where you'll find reverse auctions for merchandise, not stocks:

  • Jellyfish.com
  • ZeeDive.com
  • Atomicshopping.com

At ZeeDive.com recently, I poked around the site and spotted a "Foam Wig Head Mannequin New (Imperfect)" that reportedly retails for $7.42 going for $4.76 (a savings of 36%) with 25 minutes left. The price was set to fall to $4.70. (There were more appealing products for sale, but this one caught my eye. Go figure.)

While ZeeDive items are on sale all day long, the Jellyfish.com version of reverse auctions, "Smack Shopping", is more of an event, happening for a limited period during each day. As someone who works for the company explained to me, "New products on Smack Shopping go for an average of 45% off of retail... that's not for potting mix or rubber bands, it's for iPods and plasma TVs and other gear that people actually want." (I actually need potting mix more than an iPod at the moment, though.)

So there's your latest installment of nifty online shopping tips. If you'd like to extend this series, go ahead and send me your own best ideas.

For more money-saving advice, tips on great deals, and general investing guidance, I invite you to take advantage of a free trial of our Motley Fool Green Light newsletter service. There's no obligation, and I think you'll like what you see.

eBay is a Stock Advisor recommendation.

Longtime Fool contributor Selena Maranjian owns shares of eBay. The Fool has a disclosure policy.