A Cromwell woman has been given a chance to turn her life around after she was caught dealing methamphetamine and helping associate manufacture the drug.

Natasha Maree McCrostie, 26, unemployed, was sentenced to seven months' home detention and two years' intensive supervision in the Queenstown District Court on Monday, for nearly 18 months of offending that finally ended last August.

Queenstown police began a nine-month investigation into the activities of McCrostie and two associates early last year over suspicions they were manufacturing and distributing the drug.

Analysis of McCrostie's cellphone showed text messages in which she arranged drug sales in August and September of 2020.

In Auckland in March last year, she bought 2.2 litres of acetone - a precursor substance for manufacturing meth - and equipment including digital scales and funnels.

The following month, after pursuing a vehicle linked to the defendant, police found $3500 cash inside it that they believed to be the proceeds of drug sales.

A subsequent search of her Queenstown home uncovered a bag in her bedroom containing $19,800 in cash, although her associate later claimed ownership of the money.

A range of security measures was evident at the property, including a cellphone blocking device known as a 'signal jammer', anti-spy signal software used to detect hidden bugs or trackers, and sensors and CCTV cameras around the property's exterior.

McCrostie's banking records showed that between November 2020 and March last year, the defendant received cash or ATM deposits and cash transfers from locations throughout New Zealand totalling $21,640.

Police believed the money to be the proceeds of drug sales.

She was arrested and charged with possessing material for manufacturing methamphetamine (two charges), offering to supply meth (two charges), and supplying meth.

Noting that McCrostie had been a daily meth user during her offending, Judge John Brandts-Giesen told her a non-custodial sentence was a "community investment in your future".

As the mother of a young boy, she should "grasp with both hands" the opportunity the court was giving her to get help for her addiction, he said.

"If you fail, the criminal process will become less concerned about your rehabilitation and more focused on punishment."

- Guy Williams, ODT