Can I make my own gels to use with Galvanic Spa System?


I'm considering buying a Galvanic Spa System from Nu Skin and have a few questions about it.
1) Is Nu Skin Spa System (around 0) better than the competitors (some like Paragon Portable Facial Professional Galvanic run for about 0)? If so, why?
2) Can I use my own cosmetics or gels with the system? I do not like the fact that Nu Skin gel contains parabens, artificial preservatives which mimic some body hormones and therefore are harmful. Also, I do not want to be dependent on the Nu Skin gels and keep buying them all the time. If I can use my own gels, is there a way to charge it positively/negatively?