Google Products may be a Google property, but the listings there are created by merchants who sell those goods. Have you submitted a product feed for the items you sell?
I found for my one client who has a small ecommerce site that this helps to offset the fact her site was pushed down by exactly what MrFewkes describes. At least her site shows up under the "products" results which is, I think, a more fair playing field when it comes to competing with larger sites.
And for what it is worth, the site has been around for 12 years and up until last spring, always appeared in the top five results for her category. Draw whatever conclusion you like, but I think it support the OP's position.