My bad, I thought you were just going to make a simple adapter and solder a USB port/similar on the controller either in place of the original or as a splice.
Alas whenever I need ports I either standardise the plug as above or someone likely has something wasting space in a box and will give it to me or I have some plastics manufacturing kit.
Easiest way I can see is to make one using some casting material and inserting an existing end. While I can not speak for Australia I know electronics here in Europe and the US are greatly impressed with packaging and this very much counts as making your own. Also you can always make a kludge of a port (working but not so sturdy) and replace it as and when you obtain a snes/nes to cannibalise.
One further idea is you take your working nes/snes and simply solder or otherwise connect wires to the points where the nes/snes joins the motherboard of the nes/snes
