If possible, it would be great if there could be some kind of implementation of a reputation system for sellers. Because in dark markets reputation is everything and crucial for business transactions to happen
Edit: I think it would be easy to have a "star" rating system where it would show average out of 5 stars and the number of people that reviewed, or clicked a star rating.
Problem is if that could be gamed somehow. That is why I previously suggested an i2p review site/forum.