So there are a number of things to consider. I'd start by trying to do a locker setup at an airport, and charge in the $30-40 range for the first day and a discount for each additional day, and include the charger. More or less a brandable app that would combine the controls of the OneWheel and handle the transaction with the rental company. This takes away the biggest cost in staffing the location, and offers up the ability for OneWheel owners to snag one without bringing a checked bag. By doing it at the airport, someone could land, and on the way to their hotel shuttle/metro/?? they could grab their OneWheel that would be their mode around town.
The follow on would be the location based rental, in a tourist / flat beachy area where you'd have a staffed kiosk with a learning ground to 'try' a OneWheel for $5-10 and apply that to a rental. $30 for 4 hours is about as high as I would go, and I'd do a family style, multiple rentals on a single transaction discount, so a couple could cruise without spending $100. Remember, the cost for a Zipcar is less than $100 for a day, and that includes insurance and gas.
The more I think about it, the more I believe that a rental model that's tied to the app on the phone, where someone could extend their rental time, would be key. As a security feature, I'd build it so the app pairs with the OneWheel and if it goes offline for an extended amount of time, I'd want it to check in. In a perfect world I'd team up with Lyft/etc to provide a 'return to home' for those renters that got a little ambitious with their OneWheel adventures. Tie in social media tagging & such to offer extra time or a loyalty program.