With tens of millions of registered members and more than 12,000 items listed, eBay is, without a doubt, the world's largest Internet marketplace. And you can buy just about anything there--from CDs, movies and vitamins to first edition books, new businesses and even someone's last breath of air. But--what you want to know--is it the place to shop for fitness equipment?

The answer is yes, but that's if you don't mind sifting and, in most cases, bidding.

On a given day in June 2007, there were 1,026,771 items listed under the "Sports" category; and there were 344,705 items in the "Sporting Goods" subcategory, which is broken down into more than three-dozen subcategories. Under "Exercise & Fitness," a "Sporting Goods" subcategory, there were 7,146 items. And that subcategory is divided up into six subcategories. Hope you're not too confused.

On that given June day, I took a look at several fitness products sold on eBay. I wanted to find out how low prices on new (never been used) popular or quality products go on this mega auction site. The good news: They can go pretty low.

One product I examined was Total Trainer, and there are several models listed on eBay. I zeroed in on the 3000 model, which is supposed to be comparable to the Brinkley- and Norris- endorsed Total Gym 3000. On eBay, Total Trainer is offered in two pricing formats: Name your own or Buy It Now (skip the auction process) for $277. Off eBay, Total Gym retails for, on average, $500.

I also compared a few other infomercial-marketed products. One, a knock-off of the Fast Abs bodybuilding belt, an electronic muscle stimulation device, runs for about $10 to $15 on eBay (with free shipping). Off eBay, the real product will cost you around $30, plus shipping/handling. Another, Smart ABS, is priced at $50 on eBay; off, it ranges between $70 and $80. A third product is a Fitness Quest glider similar to the Tony Little Gazelle Freestyle Elite. Buy it on eBay and you'll pay roughly $220, almost half of what you would spend at Little's official site.

The last product I checked out was Jolie Weights, one-pound attachable fitness shoe weights introduced this spring by Jolie World. At JolieWeights.com, these weights cost $19.99. An independent eBay seller was auctioning them for $14.99. That's a 25 percent savings. Plus, shipping/handling charges are exactly the same.

The bottom line is: You will find some good deals on eBay. But there are a good number of duds there too. The best advice? Do your research before buying. Compare prices; read the fine print; ask the seller whether it's a discontinued or irregular product; and be vigilant of bloated shipping/handling charges (a common practice among eBay sellers). A final tip: before buying anything, read the seller's reviews, where buyers post their positive or negative shopping experiences. If the eBay seller has too many negatives, then you may want to pass on the deal. If the seller seems legitimate, and you've confirmed it's a steal, jump on it. The price--the product-- may be gone tomorrow.