The size of the darknet markets economy can be problematic to estimate. A study based on a combination of listing scrapes and feedback to estimate sales volume by researchers at Carnegie Mellon University captured some of the best data. A reviewed 2013 analysis put the Silk Road grossing $300,000 a day, extrapolating to over $100 million over a year. Subsequent data from later markets has significant gaps as well as complexities associated with analyzing multiple marketplaces.
18,174 – October 2013, Digital Citizens Alliance, 13,472 of which were on Silk Road in November 2013
41,207 – April 2014 Digital Citizens Alliance
33,985 – May 2014 The Guardian via Reddit
43,175 – July 2014 a report by the BBC
65,595 – August 2014 Digital Citizens Alliance
51,755 – December 2014 Digital Citizens Alliance
68,835 – March 2015 (pre-Evolution scam), Digital Citizens Alliance
68,322 – April 2015 (post Evolution scam)

James Martin’s 2014 book Drugs on the Dark Net: How Cryptomarkets are Transforming the Global Trade in Illicit Drugs discusses some vendors are even branding their opium or cocaine as “fair trade”, “organic” or sourced from conflict-free zones. In June 2015 journalist Jamie Bartlett gave a TED talk about the state of the darknet market ecosystem as it stands today.