"My checking account, as of this morning, is $25.97. Somewhere deep inside me, I'm still afraid I've thrown all our money away," he said.
"I am sure I will feel that sense of relief when I see the first customer walk in the door. Once they are lined up out the door, I'll be doing a dance on top of the glass counter."
Markus, 53, was a step closer to dancing Monday after officials in Washington issued him one of the state's first 24 marijuana retailer licenses.
He plans to open a store this week in Union Gap, Washington, one of two U.S. states that have legalized the sale of recreational marijuana. Sales started in Colorado in January.
Markus got the idea after his sister died from an accidental drug overdose some four years ago. She suffered from chronic pain and took heavy medication.
"She passed away and in the process of talking to people about it, it came up that she would have benefited from using a cannabis product. It motivated me," Markus said.
At that point, medical marijuana was legal in Washington, but recreational marijuana sales were not, so he decided risks were too great to open a store.
That calculation changed when Washington changed its laws.
"I was making $25,000 a year, selling cars and supporting a family of four. This was until last month. I went through and pulled out all my funds in all my 401ks. And put into this -- with lots of help from friends, lots of donated labor. This is a true labor of love," said Markus, who does not smoke.
"I don't want to give the impression this is a hippie thing. All my friends and family pulled together to build this thing. We have everything in place to be successful," he said.
Maureen Cooke, 72, is equally optimistic. She, too, received one of the state's first marijuana retailer licenses.
Cooke is set to open her store in Langley, Washington, where she expects rapid growth, "maybe $5 million in sales" the first month.
"If it's anything like Colorado, goodness! As long as we have product to sell, we are going to sell it. This is my retirement," she said.
Public opinion has rapidly shifted toward softer policies on marijuana use.
In January, a CNN/ORC International survey found that 55% of respondents wanted to see marijuana made legal. That's up from 16% in 1987, according to the CNN poll and numbers from the General Social Survey.