Bone mass off the scale? (>=8.0kg)

I got one of those scales that use an electrical impulse to measure something and estimate bone mass from that and age, sex, height, weight. Now it's only an estimate, but the box says the measurement range is up to 8.0kg, and i measure 8.0kg. Does anyone else have such a good score as me or even come close? How can i get more accurate info without breaking the bank (and not just by walking on to the floor of the building)?