I have done both, high dollar kit (AAW $500+), and purchase a used 80's chevy fuse box and new wire, terminals and connectors (Packard 56 in my case, I ran into minimum order costs). Wire had no color code and no markings. Had to sort out all the cut off wires on the donor fuse box and no schematic or wiring diagram. (The diagrams are online however). The only thing you get out of it is seeing if you can do it. No appreciable money saved over a generic, minimal circuit, kit on sale. You have to kind of know what you are doing to DIY wire a truck. But it's not Rocket Surgery.
BTW: You don't need to rewire to convert to 12V. Not sure if that's why you are "rewiring". Seems like EZ Wire is the lowest price.($185) The wire in the cheaper kit is the same quality gxl automotive wire as the high dollar kit.
