You might not break a leg. Maybe a wrist!
It's almost guaranteed that you will experience some kind of injury, from bruises to more serious ones.
Did you really only pay that little for it?
Gawd, I have seen a three-wheeler in forever. I used to have a 350X back about 10 years ago. I blew the motor, and had the guy at the local shop bore it and raise the compression. You basically had to be a mule to get it started, but it sure would go like hell.