Balance bikes for kids are common in Europe. I believe they're making their way to the United States. While the principle - teaching kids to balance without pedals and training wheels - is spot on, the price is not quite so practical.
So let me save you some money: simply do not put the training wheels on the bike and remove the pedals. Let your child push/scoot himself along with her feet. Pretty soon you will see her raising his legs and feet off the ground and coasting. You'll see her turning and maneuvering the bike normally except she is not pedaling. After a fair amount of time (it's your child, you be the judge!), put the pedals back on and watch her go!
Balancing is the hard part about riding a bike. Pedaling is easy, so by putting the training wheels on, you've not helped the child "learn to ride a bike;" you've simply provided a temporary source of balance that, when removed, will put the child back to square one in actually learning to ride.
Both of our younger two had never been on a bike prior to our return to the United States last year. When Big Girl's old bike arrived on the truck from storage, we pulled the pedals off and both of the kids coasted around for a good month or so. We bought The Boy a bike, came home, and off he went immediately! Baby Girl was 4 and was also whizzing around in no time!