I have a general question that could apply to any very competitive product marketed by affiliates. Is it worth setting up a unique site dedicated towards a specific affiliate product, if there is already tons of competition for this product? I mean, to my mind, the reason there is competition is that the product is probably a good seller. However the ability to rank well for the product on Google, and drive visitors to your site as opposed to your competitor's must be quite hard.
Like Luigi said, it will be more difficult to promote a product that is already being promoted heavily. I'd recommend finding one that does not have as much competition to start with. This way you will be able to get the basics down and move onto more competitive niches.