Emsculpt for arms and shoulders (off label)?

Initial FDA approval of Emsculpt is for the abdomen and buttocks.  Emsculpt will likely be utilized off-label eventually to treat other areas than the abdomen and buttocks.  BTL, the company that developed the Emsculpt device is working on creating applicators to treat other areas of the body.  Stay tuned.

When trying to target specific muscle groups, high current electrical muscle stimulation is superior to an electromagnetic field. The Trusculpt Flex uses 30 mAmp of current (vs commercial EMS devices that use less than 10mAmp) which can cause the same supramaximal contraction as the Emsculpt but the pads cover twice the area per site treated and the types of contractions can be bidirectional as well as twisting that helps develop muscle in a way closer to how a good workout regimen will incorporate multiple types of contractions to work different sides of the same muscle. The Flex can also treat more areas at once, ie Biceps, Triceps, infraspinatus and supraspinatus (rotator cuff) or gluteus medius, Maximus, minimus as well as obliques, transversus abdominis and rectus abdominis. 
Building muscle is not a field of plastic surgery or dermatology. If you are serious about getting the best results at the best price, see a specialist in musculoskeletal medicine, who understands how muscles work together, how they are built and maintained and who has done enough  research into the field to know that the Trusculpt Flex is the most advanced technology on the market today for this purpose.