WHEN Ashley Bayuk sold a washing machine to her mysterious neighbour this week there was no indication that he was part of an international, multimillion-dollar drug syndicate that was about to be smashed by police.

She believed he was a bargain hunter, looking for a cheap buy at her garage sale, but was stunned when the man's fresh-faced partner pulled out a wad of cash to pay for the appliance.

Officers collate plants in the driveway of the Somerton Road house Greenvale. Credit:Jason South

The neighbour's rented home was packed with a sophisticated lighting and heating system to cultivate marijuana, which was part of a $20 million-plus haul seized by police in a massive drug bust.

The Greenvale home was one of 29 properties simultaneously searched by more than 250 police in morning raids that netted 5200 plants and cash.