Web development

I need a new website. I need you to design and build a website for my small business. I would like a website where contractors mainly but home owners can go on aswell and list items that they have either left over from a job or that they purchased to do a job and never did it for instance if there was a plumber and he had 40 ft of left over copper pipe he can list it on the site for a cheaper price then it would cost new and other people would go on the site to look for deals it needs to be set up like craiglist sorta where it's by city and state aswell as by different category's like plumbing ,electrical,building supplies ,Paint etc now the website needs to be set up where it makes a 10% profit per transaction also the buyer is gonna need to ask the seller questions so they need to be able to communicate with a instant message and the people are gonna have to create some kind of account with email also on the website it's going to be needed to be set up for future advertisement such as a page that sais contractors in your area and special ads