The recent recreational marijuana legalization in Colorado and Washington illustrates just how mainstream cannabis consumption has become, but despite an unprecedented demand, industrial grow operations are having a hard time turning a profit. The Wall Street Journal reports on the billion-dollar industry of legal pot production, finding that the labor-intensive nature of the business, coupled with a lack of access to investment capital, are making it tough for growers. And of course that isn't helped by falling prices. According to a wholesale service called Roberto’s MMJ List, the average cost of a pound of high-grade herb in Denver has fallen from $2,900 in summer 2011 to $2,000 this year.