I've only done it a few times but I've had good luck going to flea markets....I'll generally put up a sign that says demo ride every hour on the hour and usually a crowd will gather (For liability reasons I do the demo riding)....It's also amazing to see all the lookers as they pass the bikes because most people will have never seen a motorized bike before.
There are lots of selling points on an MB:
1) It's Fun. The sensation is different from a motorcycle, because it handles differently.
2) It has very good mileage.
3) No license
4) No Road Tax.
5) No insurance.
6) You can carry it.
7) You can still pedal without the gas.
8) You still get good exercise when trying to start it up, or when the engine is having difficulty going uphill.
Many of our customers have started business just by riding the bike around the neighborhood. Most had no intention of selling these kits pre-mounted on bikes, but had purchased the kit for their own personal use. After being stopped many times while riding, that light bulb turned on and their entrepreneur spirit set foot.
If you have the time to just ride around and have fun, you could make good money. Good luck!