This site offer a good list and details and comparisons of Darknet marketplaces.
https://www.deepdotweb.com/2013/10/28/updated-llist-of-hidden-marketplaces-tor-i2p/Darknet marketplaces are not just the drug dealers. Nearly all of them deals a wide range of products (P2P). Bitcoin would be the major payment processor. You might need tor browser to access the marketplaces. But surely some things really dark on these markets. If you are under a highly oppressive government you should rather be careful accessing and even talking about such markets.
Isn't that post more than 2 years old?
OP should probably start off from the hidden wiki.
That would lead him to a lot of marketplaces.