Many people who rely on medical marijuana to treat chronic pain and other conditions are having trouble paying for it, according to NBC News.

Medical marijuana can be more than double the cost of street marijuana in many places across the United States, the article notes. The cost of medical marijuana varies by state. In New Jersey, an ounce of medical marijuana costs up to $500, while the cost is $265 in Michigan.

Patients need to qualify for a medical marijuana card. The cost of a card varies widely across the country. In Minnesota, Arizona and Oregon, the card costs at least $150. In several other states, the cards cost between $50 and $100. The cards must be renewed and paid for each year.

“People have been accessing marijuana through the illicit market well before medical programs existed,” said Scott Smith, spokesman for the Minnesota Medical Cannabis program. “Until the products are covered by insurance or the industry is well developed, including removing federal barriers that exist for the industry, price will continue to be a problem for many individuals.”