Build an online marketplace for services

Hi, I need a website developed with the following features: 1. Ability for the client user to post competitions 2. People will work according to the specs (small jobs basically) of the competition and submit work, which will either be watermarked (in case it is a jpeg file) or will be copyright protected by some other formula 3. Payment to be released only to competitor whose work is chosen by the user. 4. Reporting on user and competitor and feedback on both 5. Integration of Escrow account(manged only by the site admin:- this feeature will be discussed in detail later) 6. Integration of payment via paypal, credit card, wire transfer, debit card. I am experienced in outsourcing projects hence I am not interested in freelancers who just put up "PLACEHOLDER BIDS" to get my attention. Such bids will not be entertained. Bid only after thorough understanding of what is required as a precaution start your bid with the phrase "I read it" only then will I contact you. I am open to your suggestion on technologies.