Licensed state marijuana retailers face consistent supply shortages even as the black market continues to thrive.

Legal sales of recreational marijuana brought in over $445 million in revenues for distributors and growers in Massachusetts last year, says the Cannabis Control Commission.

]According to MarketWatch, investment analysts predict that the state could bring $900 million in legal weed sales in 2020. Against the state’s gross domestic product of around $570 billion, this could represent as much as 1.6% of the state’s economy.

Still, there isn’t enough marijuana to meet the steady demand. Prices are some of the most expensive in the country, inflated by the limited supply. By law, retailers can only buy from licensed growers in the state, yet the scarcity of licenses slows the flow of the hot commodity.