Are you specifically after the GH60 or any 60% with standard features is good for you?
Also, you should clarify what parts are you looking for. Usually a 60% build requires a PCB, a mounting plate (although this is optional), switches, a set of stabilizers, a case and keycaps.
As for actually building it, how do you rate your soldering experience? There's actually not much to know beforehand to assemble a 60% keyboard but knowing that won't hurt.
Lastly, I assume you're looking for low costs, fast shipping, so where in the world are you?