There are a ton of new bikes coming out each year. In 2013 and 2014 there have been a ramp up in electric powered and electric assisted bikes.
One of the best electric bikes for the money is the Currie Technologies eZip Trailz bike. It only cost $450! It has a range of 20 miles just running off the battery and a top speed of 20mph. The $2,500 electric bikes typically have a top speed of only 22-25mph and a similar range. So, this bike is a really good deal.
Now, if you already have standard mountain bike or hybrid or street bike without a rear shock then you can add on a battery and motor for around $299 and make your current bike an electric bike! It is the same system as the currie bike. 20 mile range and 20 mph speed.
Checkout more over at commuter bike hero
See more about electric bikes http://en.wikipedia.org/wiki/Electric_bike