Till that coming day, this called "DEM" market hasn't any important role. Personally, i don't encourage users to buy/sell illegal stuff, and if so, it will be a great mistake to do it in live mirrors. Imagine children who will be able to use it to buy drugs or arms in simple steps, this is why it is a little bit safer to lunch this kind of services in darknet which requires a lot of complex steps to reach it.
I wish i saw you building an app that can ensure anonymity for its users so they can share what they want in freedom. Something like for journalists or reporters or those who can't freely speak.