Hi Raj,
Given no ones answered - I thought I'd step in with helping to get the ball rolling....
It sounds like you want to scrape websites with collecting reviews on many products... Is that correct? There are various services and tools which can do that for you... One tool comes to mind is scrapebox which also has many other uses.... You may also want to investigate hiring freelancers to help you too...
Saying that I would be careful in doing that... I would investigate the legalities of such a business model especially with regards to copyright and perhaps work around to use citation of sources when you compile the data... But I'm not a lawyer so I cannot advise any further...
In addition to that - why not encourage real people to visit your site and leave original review comments? I would write a detailed review and then encourage people to add comments/feedback on their personal experiences.... as then you have original content which is always better!
Also have a think about this... Lets say you develop this amazing site and after a few years its really taken off... How would you feel if someone came along and scraped your website content so that they could create a similar site??? Hence why I mentioned use of citations and references which may appease the originator...
On that note - wishing you the best of luck!
Cheers,
Sid