So you're all set to buy that Widget Pro from Amazon, but just before you add it to your cart, you stop and think: "Am I getting the best price?" PriceTrace, a new add-on for Firefox, aims to give you a one-click answer.

It's not perfect, and I should tell you right up front that it adds yet another toolbar to your browser. If you can live with that, you'll probably love the convenience it affords.

There are two ways to use PriceTrace. First, you can type a product name, UPC, SKU, or URL in the search field and hit Enter. In an instant you'll get price-comparison data in a new tab, along with a snapshot of PriceTrace's interesting, informative price-history chart.

Even better, if you're already looking at a product on a site like Amazon or Newegg, just click the Trace the item on this page button. You'll get the aforementioned comparison/history results in a new tab.

Unfortunately, this doesn't always work exactly right. Newegg's product page for the Creative Vado HD pocket camcorder, for instance, calls it the "Creative Vado HD Black Pocket Video Cam"--and the resulting comparison page shows only the Newegg listing.

Run your own search for "Creative Vado HD," however, and you'll get tons of results. PriceTrace needs to tweak this one-click search option to be a little smarter about querying its own database.

Still, the site offers several other handy features, including price-drop alerts (it notifies you via e-mail when a particular product reaches a certain price) and an Editor Picks section that showcases products that have had big price drops.

If you love to shop online, PriceTrace can help you save money in the Web's virtual aisles.