Flippa is a marketplace to sell and buy internet properties like domains,website and applications.They are making good money by commission on sale as well as on every listing. My friends are into flipping business of websites and domains and they are interested in creating a website like that.
I generally publish blog posts about free themes but as there is no other solution i think you should try these options.
Some themes that can be further transformed to look like flippa or a much better site. You will be requiring programmers and designers to further edit and make it look and work like your desired website. You might want to remove these maps and other features from these directory themes.
1)ListingBuilder : Basically a directory theme
This theme comes with price range and category filter, these filters can further be altered to do work like earnings stats or website traffic. It is responive and will work on mobile and other devices.You can define your pricing plans. Reviews,widgets and much more.3 different pages for listing categories. View the demo to understand it
2) This theme is also looks great for this purpose.
besides these themes there are various clone scripts for it that i would not recommend reason is badly coded scripts can leave you vulnerable to attack from hackers. If you have any ideas please share with us.
It is not a easy task to create a site like it, simply because they were among the first to try and implement it, they designed their site according to users(buyers and sellers) and lots of features like safety issues for both of the sides. Now there is another site freemarket.com which is also a good site but they are lacking several factors that makes them a bit backward in this segment.