Boulder County Caregivers offers 16 glass jars of marijuana with names like Skinny Pineapple and Early Pearl Maui, priced at $375 to $420 an ounce. There are marijuana capsules and snacks made with cannabis butter, such as rice crispy treats.

Co-owner Jill Leigh urges customers to try a syrupy tincture she calls "the Advil of medical marijuana." A drop under the tongue gives less of a high but the same pain relief as smoking, she says.

Leigh's sales are legal - and taxed - under Colorado's voter-approved medical marijuana law. Her marijuana dispensary and nearly 60 others serve a rapidly growing number of users with little oversight. Critics of the system say it's prone to abuse and point to a growing number of younger patients. But a recent state effort to impose more controls failed.

More than 9,000 people are registered in Colorado to use medical marijuana with a doctor's recommendation - up 2,000 in the past month.

The total is expected to rise to 15,000 by year's end, according to the state health department, which blames the rapid increase on patient confidentiality guarantees and federal plans to stop raiding medical marijuana operations, which the U.S. government considers illegal.

Since December, the average patient age in Colorado has dropped from 42 to 24, raising more questions about abuses.

Last week, the state health board rejected a proposal to limit suppliers to five patients. Dispensary owners said the plan would force many to close. Others, including Leigh, say Colorado should better regulate its dispensaries to deter abuses. But Chief Medical Officer Ned Calonge said he simply doesn't have that authority under the 2000 law.

Some towns are stepping in. On Tuesday, Breckenridge will consider rules to keep dispensaries away from schools and restrict their hours to prevent thefts. Police Chief Rick Holman said the ideas came from Cannabis Therapeutics, a Colorado Springs dispensary believed to be the state's largest with 1,400 patients.

The Denver suburb of Commerce City also is drafting its own rules. In Boulder, police have reached out to dispensaries after thieves stole two 20-gallon barrels of marijuana from one business in June.

Leigh's waiting room could be found in a dentist's office, save for coffee-table reading material that includes a copy of High Times and a Timothy Leary book. Spice jars feature samples of marijuana available for sale. All sales are by appointment only, and Leigh's business collects about $10,000 in sales tax a month.

Leigh's patients are mainly middle-aged women with multiple sclerosis and men coping with hepatitis C. One employee said he takes tincture drops to help prevent seizures. A customer, a jiujitsu coach, said he uses it to treat pain from four surgeries and regular fights.

Leigh said she and her husband, who uses marijuana to cope with degenerative disc disease, started selling marijuana he was growing to avoid running up against the law.

Patients can only possess up to 2 ounces of usable marijuana under Colorado law. But a patient or his designated caregiver can grow six marijuana plants - but only three can flower at any time.

Today Leigh, a self-described soccer and karate mom, has seven employees, offers health insurance and plans to add 401(k) benefits. She worries federal agents might raid her business, even though the Obama administration says the government will stop targeting medical marijuana operations that are in line with state law.

For luck, Leigh hangs Tibetan prayer flags in her offices and has a statue of the elephant-headed Hindu god of Ganesh. She says a California dispensary that had both items was spared in a recent federal raid.