Chagrin: Thanks very much for the suggestions and the link. I will keep these things in mind as I move forward with my project.
Steve: Yes, you're correct, I really only need to turn the motors on and off. Nothing fancy. I think I will start by trying out your suggestion of using a 3V power supply without PWM. I appreciate your points about controlling the vibration intensity, because there's a possibility I will need to do that somewhere down the line (but not yet). So thanks for that information. I might need to start all 5 motors at the same time, so I will look for a power supply with at least 2.15A.
Thanks to everyone for your responses. I think I've got the info I need to get started with my project, but if anyone else has any pointers, feel free to chime in. Now I need to order some parts 