If you like the Enertia but not the price tag, consider Yamaha's Electric Commuter EC-02. It's just $2,000. It looks a lot like the Enertia electric bike, just smaller and much slower. The Enertia's top speed is 50 MPH while the EC-02 can only go 18 MPH. Enertia says their "bikes are not associated with Yamaha. The Enertia design is a clean sheet (not a conversion or extension of a previous design) and was built from conception to be the first street legal production electric motorcycle."
EC-02 is 30 percent recyclable and it can fold away easily. There is a special Ipod edition of the EC-02. That version lets you drop your Ipod in a special dock. You can also swap out the battery in the EC-02. It's pretty tiny and slow but I guess it shows the Enertia is worth the cost. If you ever said, make a cheaper Enertia, well, here is something like what you would get. Go below the fold to see the EC-02 in the wild.