A passenger-only edition costs $6 billion. Musk says it will take 20 years to build. So here's how he gets to $20. ...transporting 7.4 million people each way and amortizing the cost of $6 billion over 20 years gives a ticket price of $20 for a one-way trip for the passenger version of Hyperloop. Here's the rundown, via his explanatory .pdf.