Call it a drug trade for investors. Todd Harrison, CEO and founder of Internet-based financial media company MInyanville, thinks cannabis "will be the single best investment idea for the next ten years."

Related: Pot Pushback Goes Up in Smoke: $20 Billion Economy Awaits Marijuana Legalization

But while the public has watched recreational marijuana take off in Colorado this year, how can they profit from it as an investment theme?

Harrison believes it will be driven by the broader legalization of marijuana, inspired by states' need for tax revenue. He points to expectations that legal marijuana use is expected to generate $134 million in tax revenue for the upcoming fiscal year in Colorado, the first state to allow recreational marijuana. That's  nothing to sneeze at, and Harrison calls the state the "litmus test" for broader legalization. Harrison also cites the expected decline in crime rates and  prison populations as powerful incentives to decriminalize  marijuana.

Related: Post Office Looking Into Shipping Beer, Wine & Liquor But Not Marijuana

The New York Times reports that half the states in the U.S., including some in the conservative South, are currently considering decriminalization of the drug or legalizing it for medical or recreational use. Oregon and Alaska are the likeliest to legalize pot next year. Twenty states now permit the use of medical marijuana now, while Colorado and Washington have legalized it for recreational use.

Related: “Marijuana Is a Vegetable” and Belongs in the Farmers’ Market: Pot VC

The legal marijuana market is estimated to grow  64% to $2.34 billion in 2014 from $1.44 billion, according to a recent report by the cannabis investment and research firm Arcview Group.

Wall Street currently doesn't cover the marijuana market as an industry but once legalization is more widespread, that will be the inflection point when we marijuana investing moves mainstream, says Harrison.

Currently the chatter is mostly about marijuana penny stocks. They are not what Harrison is talking about. He says those stocks are very risky and volatile, and he doesn't touch them.

But there are some "real" companies generating interest. Harrison cites the cannabinoid prescription medicine company GW Pharmaceuticals (GWPH) as an example. He's not suggesting the stock as a buy or sell, just as an example he's traded in the past. The stock has rallied more than 500% since last summer.

Advanced Cannabis Solutions (CANN), soared 62% in a single day when its stock chart was shown on CNBC earlier this week -- even though it was a mistake, and the anchor was actually discussing another company in the cannabis industry, called CannaVEST (CANV). Advanced Cannabis Solutions leases growing facilities to legal marijuana growers and dispensary operators. CannaVEST makes hemp-based consumer products. (CORRECTION: An earlier version of this story said that Advanced Cannabis Solutions soared 62% in a single day when it was mentioned on CNBC earlier this week.)