Theme recommendation

Hi,
I need advice on what would be the most effective way to build a site that displays ads for used gear similar to theses links: http://www.guitarmart.co.uk/

http://www.secondhandboards.com/

http://www.preloved.co.uk/adverts/list?id=2117&keyword=mac&x=0&y=0

http://www.a1surf.com/classifieds/shortboards/classifiedcategoryid/1/showallclassifieds.aspx

The first and second are the closest to what I want.

I need a sophisticated search tool like in the second link, the ability to implement Google Ad words and banners to monetize the site and users need to be able to post ads entering photos and selecting categories, furthermore the most recent appear on the homepage.

Any help and advice you could give me would be much appreciated.
Thanks in advance
Oliver