Based on my little experiment above, for the quantities I am using and by the time I factor in my time the difference purely in cost between the two options are fairly minimal (with drawing my own wire coming in ever so slightly slightly cheaper). If I was to produce more wire then it would be a no brainer (economy of scale) although I don't really like the idea of keeping large amounts of gold on the premises (at the moment I order as and when I need it). I think for me it will come down to how busy I am at any given time.