They needed $4,000 to start.

Cody Sadler, then 21, sold his dirt bike. His father, George Sadler, sold some of his tools.

They bet it all on four marijuana plants in a garage in San Diego -- and turned on the grow lights.

Eight years later, the father-and-son team now expects to sell $70 million worth of legal medical marijuana vape cartridges in Michigan and California.

They own Platinum Vape, a company whose products are in nearly every provisioning center in Michigan and whose billboards greet drivers on every major highway across the Mitten. The Sadlers haven't taken on outside investors, and remain a family business.

"We put all our money right back into the company," Cody Sadler said, explaining how the company has remained in the family. "We just promote an honest product for a great price."

Family business is familiar to them. Cody Sadler worked for his grandfather’s electrical company, as did George Sadler, up until it shut down. Father and son were looking for work.

"I was looking for other jobs and trying to be a motorcycle salesman," Cody Sadler said. "I watched a documentary on cannabis and growing. To me it was pretty amazing. I knew nothing about it."

Dad George was on board with the new venture, which started with a crop of marijuana in their garage. They quickly escalated from growing to starting a delivery service, to later starting three California stores under the brand Nature's Leaf. In 2015 vape pens were new on the market and were flying off the shelves at their stores. Father and son recognized a new opportunity.

New regulations pushed them to shut down their stores in California and focus on making their own line of medical marijuana vape pens. In China, as they were picking out the c-cell hardware for their pens, their Chinese business associates suggested a brand name: Platinum. It stuck.

Looking for place to launch the brand, the Sadlers turned to Michigan, where they both have roots. George Sadler is from Detroit, and Cody Sadler went to high school in Ludington. At the time in 2016, laws were changing in Michigan to add regulations to the medical marijuana industry.

"Michigan right now is sitting in the top three cannabis states," Cody Sadler said. "I truly feel it's going to expand like crazy."

In Michigan, Platinum Vape has a licensing deal with Choice Labs in Jackson. They're building a separate building at the Choice Labs property.

Cody Sadler said Platinum Vape products are in 95 percent of the provisioning centers in Michigan, and has plans to launch new lines of medical marijuana edibles and flower in December.

"It became such a thing for people to use carts versus flower just because of how convenient it is," Cody Sadler said. "They're easily a number-one seller."

Platinum Vape also has its sights set nationally: they’ll be expanding to Nevada in November and Oregon shortly after, Cody Sadler said.

Contact an editor at lansing@mlive.com. Read more from MLive about medical and recreational marijuana.