Web App for Comparison Website

I need a web app that will work as a comparison website. I need it to fetch data from a few websites (3,4 maybe more) and then present the results in a tabular form. The web app should be scalable so use ruby on rails, django or something similar. There needs to be some sort of config file or control panel for admin tasks. I also need to easily manage adsesnse code , affiliate code and analytics. I have no problem if an existing open source CMS is modified and used , I will leave it up to the developer to suggest the best possible solution. Please message for more details. Also please tell me the pros and cons of the framework you plan to use for this. Thanks in advance, Regards