The New Zealand Drug Foundation says last year's law change effectively banning psychoactive drugs has done little to subdue the market.
It says stockpiles of synthetic cannabis have gone underground, but they are still for sale and some people are still making a lot of money.
The Drug Foundation says there is a thriving black market in psychoactive drugs and the Government has a responsibility to do more to keep users safe.
A North Shore man, who doesn't want to be identified, told 3 News he has been hocking off synthetic cannabis he bulk-bought on the cheap just days before a law change basically banned it.
Four-thousand packets of the stuff were on-sold with a 400 percent mark-up to dairies around Auckland.
3 News cannot name him for legal reasons, but court documents show he grossed close to $40,000 in five months.
Neither the police nor the Ministry of Health would be interviewed for this story.
In a statement the police say they are continuing with "controlled purchase operations" – that's undercover stings.
The ministry says by its very nature the size of the black market is difficult to assess.
But a police source has told 3 News cases like this are "the tip of the iceberg".
The Drug Foundation believes the black market is thriving and says others are starting to realise that.
"Some people do recognise that the black market is a free-for-all. It's the Wild West and people are putting themselves at risk," says New Zealand Drug Foundation chief executive Ross Bell.
Statistics released to 3 News under the Official Information Act show in the first eight months since the law change, there have been 63 convictions for selling or distributing psychoactive drugs and another eight cases proved.
That's a total of 71 – an average of two convictions a week.
It seems the product being pushed may not just be recycled stock that was available before the law change.
"We are also seeing new substances coming in across the borders, new synthetic cannabis products and products that mimic ecstasy and mimic LSD," says Mr Bell.
The Drug Foundation wants government agencies to make public all information they have on any of the substances they have tested and to allow users to have products they have purchased tested at a neutral venue.
"That law is now not working, so the Government has a responsibility to provide an early warning system where drug users are given good honest factual information about what is out there," says Mr Bell.
3 News
