^Use Ebay, there's all kinds of different ferts on there, and cheap too. DynaGro makes some ferts with all 16 nutrients, including all necessary trace nutes, and is very easy to use. That's just a suggestion, and the same stuff I use.
Also, I agree that you should start at 1/4 strength, then work your way up, if you plan to go with the MG fert. MG will work fine, as long as you plan to use CalMag or Epsom salts along with it. It doesn't have enough calcium and magnesium, IMO.