Build a Website

I am building price listing website. Using this website, users will be able to search for various goods such as eggs, toothpaste etc, and a list of all places where this item is present will be displayed along with price and other details. The website will be driven by a database which will contain information about various items, where they are present, whats the price etc. The website will also provide an interface so users can add information to this database. When users will search for the goods, they will get a summary list of all places; this list should be compact, and have brief information such as price, address etc. There will also be icons to like a list entry (will be added to the like list of the user), remove an entry (will not show this entry again), add to cart (adds the item to a cart). The list should dynamically appear as users scrolls down, infinite scrolling. This should be fast and responsive. When user clicks on a list entry, it (only that entry of the list) should expand expand inline (not a pop up window by expand below) with many more details including some images. When user clicks again or click at some other place the expanded entry collapses. The website should also contain Blog pages, a Forum page, pages for news feeds such as top 10 deals, etc. and all these should be nicely integrated with the above search. Users should also be able to create account with Facebook/Google and all their information (including their search history and cart) should be saved in their account. This is a big project and our budget is flexible and high. We want very high quality website that can scale to 100,000s of users and provide seamless user interaction. I will provide more information as we start to work together.