A lot of money is being made from selling illegal drugs in this country. Who's making it, who's taking all the risk and what are the factors that decide what drugs YOU might be taking?

In the fifth episode of From Zero we examine the business of drugs in New Zealand: how are illicit drugs made and sold? Why are poorer communities targeted? Who takes the risks? Who makes the money?

"You can't buy a tinny (of cannabis) but you can get an ounce of P on tick."

From 1920 to 1933, the USA conducted a real-life experiment in the economics of illicit drug markets, when it banned the production, importation, transportation and sale of alcohol.

In a new century, we continue to see the lessons of prohibition at play and tremendous profits being realised - for a few.

Prime Minister John Key dissects the drug market in blunt business terms and explains why selling P is such an attractive prospect for criminals.

"Australia and New Zealand have the highest price for methamphetamine in the developed world."

Disturbingly, it seems methamphetamine might be displacing marijuana as the social drug of choice in some New Zealand communities. Whangarei lawyer Kelly Ellis says this change is hitting our poorer towns the hardest and changing the nature of them.

"Whangarei - the town where you can't buy a tinny, but you can get an ounce of P on tick."

While big money can be made in the short term, researcher Matt Black argues that drug dealing dreams generally don't work out.

"I've never really known anyone to sustain a long term profit from it. It always seems to catch up with people one way or another."

A senior police detective, a small-time cannabis dealer and an expert on the legal weed market all chip in on the business that just won't go away.

Go to this episode on rnz.co.nz for more details