Website design

I would like for you guys to give fare bid on an ideal that I have. Please goto http://www.tradeloop.com. See the WTB (want-to-buy) and WTS (want-to-sell) Broadcasts system. I want that same thing just as they have on main page and then I need these same functions that freelancer.com uses.I want to have computer dealers post thier WTB/WTS ads on the site with describtion and photo. buyer or seller can bid but no one knows the bids but the owners of the post. Once the time allowed the best bidder gets the deal inwhich the owner selects. No contact info will be available. I want to used the same caution (Terms of Service)as this freelancer site uses between the two parties. Each party will use the escrow system to finish deals. My site will get paid by both parties 2.5% from each of what ever the deal cost. Only if a deal is completed will the site get paid. When deals are completed escrow pays the site. All memberships and postings are free