During the Crain's forum, called "The Business of Pot: The Stakes Are High," panelists addressed the complexity of transporting marijuana.  After a company makes a sale, cannabis can't simply be shipped to the buyer. In New York, for example, only the patient or a certified caretaker can transport medicinal marijuana. Some say in the near future, a courier industry devoted to cannabis products may develop.  But don't expect that in states like Connecticut, where regulations strictly forbid medical marijuana from being "sold, dispensed or distributed via a delivery service," according to local rules. Diversion—or the drug finding its way into the hands of someone it was not meant for—also is a concern for lawmakers.  "There is an exception for caregivers who may deliver medical marijuana to the caregivers' patient. Given the federal concern with diversion, I suspect at least some states would be leery of allowing medical marijuana to be distributed through a delivery service," said Hanan Kolko, a lawyer at Meyer,Suozzi, English & Klein in New York.  Pricing is another key issue for growers and dispensers, according to Derek Peterson, a former broker and money manager turned "potpreneur." Peterson owns Blum dispensary in Oakland, California, and is also chief executive of a microcap company called Terra Tech, which provides equipment for medical marijuana companies.  Another concern is how marijuana prices will be set. Pricing can depend on variety of factors including the number of regional dispensaries, and prices in local black markets.  "At least they're looking to the black market as an example," Peterson said. "If they weren't doing that, and they were just dictating pricing, then a lot of patients would gravitate towards the black market because the access is easier and the prices are better."  Read MoreStoners on the job: Nearly 10% of Americans went to work high
There’s money to be made on medicinal and recreational marijuana purchases, amid state legalization. But entrepreneurs also have plenty of hurdles to clear.