That sx mini seems a little expensive for what you're getting, for the same money you could buy what I now use, the Sigelei 100w, Lemo rta by Eleaf, 2 samsung 18650 25r batteries with spare to buy a battery loader.
There are also a lot cheaper 50 watt devices from other manufacturers. With the rapid development of ecigs I rather spread my funds and buy cheaper or older models instead of the latest and greatest.