Update: We are beta-testing support for Selling on Amazon (Amazon Marketplace). You can find more information here.
Marketplace communities such as eBay and Selling on Amazon have different feed requirements because of the fact that they handle the purchase transaction. This functionality requires a more detailed feed (with billing, purchasing, and inventory details) which we don't currently support. Right now we're focused strictly on the product comparison sites that direct the shopper to the merchant for purchasing. However, at some point we will be investigating ways in which we may expand to marketplace sites such as Selling on Amazon (formerly Amazon Marketplace) and eBay. We will certainly keep you aware of such developments!