Build a reversed classified Website

This is what we need: #Read the info, "copy and paste" answers to this post will not be answered. We need you to understand what to do before giving a quote!# It will be a reversed classified page for jobs need doing. So shortly said if you for ex. need a plumber, you can go to this site – pick plumbers – write a detailed description on what you need doing, and an e-mail and sms will go out to companies that can deliver this service. The companies then log-in to our site and give their quotes. Now the user can look through all the quotes and choose the company they feel can deliver the best service. After job done the user will then write a review of the job done and give star ratings in 3 categories. This site will have to handle a good amount of traffic and will have to be very easy to use both for end-users (the people in need of services) and companies to add info about them self. There also have to be a company directory of all companies that have joined the site with logo, a small description. When I come to think about it: It should be a little bit as freelancer.com just for more general services and products (plumbers, painter, transport, etc) within a given town/ country and not only a “sky” with services. We would like to choose one for the hole job, both the design part and the programming part. A free for life ad on this site will be given to the one that can help us!