I was looking at "push bikes" or "balance bikes" a couple of months ago where toddlers can easily reach the ground while seated in their bicycle and push along and eventually begin coasting. From what I hear, they transition much easier into riding regular two-wheelers without ever having training wheels as well.
But of course, if that gyro bike really is going to sell for ~$100, then prices are pretty similar. I guess the choice would come down to how earth-crunchy you are.