Right now it's unclear exactly what you're asking for.

Are you looking for somebody to develop a fully functional black market, which you will then use to write your book about (e.g. discussing the happenings of traders on your platform).

Or are you looking for somebody to create something basic just so you can test it out and see how it works? If the former, you might land yourself in trouble if it actually gets used as a black market... Regardless if you're writing a book on it.