How about using an ultrasound for body composition? http://intelametrix.com/FullSite/ BodyMetrix has been around for a while and has about the same price of $2000
The BodyMetrix system uses A-mode (Amplitude Modulation) which essentially uses one signal or pulse and plots the amplitude change over depth. The changes in amplitude correspond to differences in tissue. [I conclude they use A-mode from the abstracts of the papers linked in their Science and Validation section]
The Butterfly Network system is a B-mode (Brightness Modulation) one. These have traditionally had many signals and are used to create the greyscale images commonly seen when referring to ultrasound. B-mode imaging has traditionally required a fair amount more in terms of hardware, software, and thus cost.