build a website

client A puts and add on my site advertising what he has in his suburb. client b enters what he is looking for and his suburb. The website will then generate all matches in their requirements and the closest suburb. it will then allow b to contact client a and notify them of the interest and pay a deposit of as asking price. the deposit will come to me and then the details of client B will be sent to A and they work out the details. I wish to sell advertising space in the future on the site and also change logos down the track and be very user friendly. It will be similar to [login to view URL] but no where near as detailed. once created i wish for it all to automated. client a has check boxes and can upload photos and client b has check boxes so its simple and structured. Also they cannot contact each other directly though or add in any email addresses or contact info. Ideally all contact will be through the website until the deposit is made. the site will need all australian suburbs/postcodes so when they search/advertise in there area the website will automatically show the nearest client. Sorry about the basic info, dont want to give away too much of the new idea. Thanks for understanding Any questions please feel free to contact me with pricing or any questions.