Everyone seems to be scared if they see walmart or target as a competitor. Yes these sites have high PR, but that is only the main domain. If you drill down to the product level you will see many of those urls have no PR and no backlinks and rarely any SEO optimization in the tags. Sometimes, they don't even have the keyword in the url, it will just say something like "product id=898992". Surely if you used hubpages which has as high a PR and as many domain backlinks as most retailers, put the exact keyword in the title and tagged it and backlinked the url, these would eventually outrank the retailer.
This is always worth a shot on specific products, I agree. I imagine that the hubpages (or other authority platform) would automatically find its way onto page 1 in about 1/10 cases. Probably about half of these pages would be amenable to SEO techniques, which could bring them above the fold and start making money. If you can find a way to push out the content fast - and perhaps find advertisers who pay more than a measly 4% (amazon) - then it could be a worthwhile strategy.
I think it all comes down the relevancy. If Big G thinks that your website is more relevant and useful to the visitors in terms of on-page content and relevant niche backlinks, than less optimized authority sites would not be a big problem. And yes, I have seen several times a webpage from big sites such as Amazon would be ranking in top 10 and people would get scared of the competition, but the truth is that they would have only a few backlinks, would not be optimized for that keyphrase and would be ranking solely based on their domain authority. They can be outranked with a little targeted SEO practice.
