Gellish is basically applying long last nailpolish by using special products and a LED light to cure the various layers until you have nails so neatly polished they'll last up to 3 weeks or even beyond!
I bought the Red Carpet Manicure kit on BeautyBay.com with a serious reduction. I paid 90 EUR for the kit, including one colour (red). If you go to have a manicure plus gellish, it's easily 30 EUR over here. For 1 visit. Just saying.
Plus I like to experiment with these things.