11. A computer-implemented system comprising a processor with a memory configured to: extract product descriptors from a product page; receive a result of a search for prices of the product based on the extracted product descriptors; generate, using the result of the search for prices of the product, a price comparison result for the product displayed in the product page; identify, using the price comparison result, a product with selected attributes; generate a buyer button, the buyer button including a direct link to the identified product with selected attributes; generate a browser toolbar and the product page contemporaneously in a client browser, wherein the browser toolbar includes a seller button, the buyer button, and the price comparison result for the product displayed in the product page; and generate, in response to operation of the seller button, a product listing on a marketplace, wherein generating the product listing includes determining a product category and a product description from the product descriptors extracted from the product page.
11. A computer-implemented system comprising a processor with a memory configured to: extract product descriptors from a product page; receive a result of a search for prices of the product based on the extracted product descriptors; generate, using the result of the search for prices of the product, a price comparison result for the product displayed in the product page; identify, using the price comparison result, a product with selected attributes; generate a buyer button, the buyer button including a direct link to the identified product with selected attributes; generate a browser toolbar and the product page contemporaneously in a client browser, wherein the browser toolbar includes a seller button, the buyer button, and the price comparison result for the product displayed in the product page; and generate, in response to operation of the seller button, a product listing on a marketplace, wherein generating the product listing includes determining a product category and a product description from the product descriptors extracted from the product page. 13. The computer-implemented system of claim 11 , wherein the processor displaying the comparison of prices for the product displayed in the product page includes displaying an average selling price for the product.