You've probably noticed this by now: When shopping for an item, you'll see the names of several merchants that also sell that product, along with price and availability info. And if you search for something, the results will typically include offers from third-party stores.

But are these deals worthwhile? To find out, I checked with Amazon and did a little investigating. My conclusion: Shopping boutique stores through Amazon can have some real benefits, but not in all situations. You should make your decisions on a case-by-case basis after checking out offers--both on Amazon and elsewhere--for whatever you're buying.

Amazon's Take

Amazon officials say partnerships with third-party vendors support the company's customer-centric philosophy.

"It helps ensure customers are able to buy high-demand products as soon as possible," spokesperson Craig Berman says. "iPods are a great example. If we're out, they can get it from a third party."

Third parties also allow Amazon to offer a much wider selection than it could on its own. For example, Amazon sells some gourmet food items, but you can buy Madagascar green peppercorns in brine (which I use in a favorite recipe) only through GourmetFoodStore.com.

Would it be cheaper just to go directly to GourmetFoodStore.com? Not by much. The two sites' prices were identical, though Amazon charged a couple of bucks more for shipping.

I couldn't do comprehensive price checks on millions of Amazon items, but a colleague and I did price about a dozen random products from third-party merchants that sell through Amazon and at their own sites. By and large, we found little difference in the bottom-line price, though you should always check for yourself. You may find a sale or an attractive deal on shipping at the store's site.

If prices are equal, buying at Amazon can make sense: The company protects most purchases made with an Amazon account by its A-to-z Guarantee, which basically promises refunds for all charges (including shipping) if the item doesn't arrive or is "materially different" than described. (Amazon's guarantee does not cover several major partners--Eddie Bauer, eBags, Target, and others--that offer their own guarantees.) I'm certainly more inclined to rely on an Amazon guarantee than one from a small third-party merchant I may never have heard of, and that may not explicitly offer such a guarantee--something to look for when you're shopping on the merchant site.