Unique identifier for all products sold in the US

I'm going to develop a website for price comparison of products sold in the US. Price information is edited by merchants, buyers and visitors (people who didn't buy). I wonder what kind identifier can I use to identify each product? This identifier should be

• unique to each version of each product
• easy to obtain, giving that 开发者_如何学编程product at hand or only the name, images (and description, etc.) of that product showing at an online store.

Is it UPC a good choice? Not sure if this kind of questions should be asked at SO. If not, feel free to move this question or vote for close.

You will probably find that a combination of UPC and EAN will be required to cover all product types including non-US products.

Refer to UPC and EAN Bar Code Page