Your trying to rank your product url for a keyword? Indexing and ranking takes time.

If you create backlinks that point directly to the site that the products are listed on, then you're helping the site.

For me, all this has ever done is help avoid ebay fees. ex: have it on ebay with shipping then put a fee shipping available at "yousite". I will say it has saved me at least a few hundred bucks in fees and brings more traffic to my site and if you are lucky they will be back to buy again.