Have you thought about a multifunction machine? The mulifunction machines comes with galvanic and high frequency. Galvanic and Ultrasound is somewhat similar. Galvanic typically is used on clients with oily skin. As far as Ultrasound, it's great with all skin types because it tones, lifts, tightens, performs a deep clean. Galvanic is is a constant and direct current so it uses electricity. Ultrasound/ultrasonic does not use electricity but the terms refers to a frequency that is above the range of sound audible to the human ear. So it uses noninvasive sound waves to create results-oriented treatments.
In my own opinion I would get a multifunction machine and an Ultrasound. Hope this information helps you in any way!