There are three basic types of FDA-approved, home-use devices for stimulating the healing of bone fractures: microcurrent (electrical), pulsed electromagnetic, and ultrasonic. Evidence for effectiveness of the first two types is unclear, due to a vareity of poorly-controlled studies with varying results.
However, there is consistently good evidence for ultrasound, including placebo-controlled studies in rabbits, rats, and humans, which should be resistant to confounding factors. The net of the evidence is that it can heal fresh fractures about 30-40% faster and resolve up to 85% of nonunions. For TPFs that have been internally fixed (ORIF) with metal plates, the ultrasound can be used from the side opposite the plate.
The only available home unit in the US is the Exogen 4000+ , which may cost up to $2,000 new from the manufacturer and may be covered by insurance if prescribed by a doctor. In any case, you should always consult your doctor before considering use of a medical device.
However, there is a secondary market on Ebay, where Exogen units typically go for $100-200 lightly used. There is also an excellent Ebay Buyers Guide. Contrary to what that guide states, replacement batteries are easily available (from OSI or other online vendors). The unit is designed to give a year's worth of daily treatments (365) before the battery needs to be replaced. Don't expect the manufacturer to help, as they will only provide support to the original purchaser.
The unit itself is small and easily transported. It uses about the same type and intensity of ultrasound as fetal imaging.