I bought the nicest used one I could find, no cuts or crazy splices. T then took all of the looms and tape off, cleaned and de-greased the crap out of it, let it dry. Then I added 4 wires to it (fuel pressure, egt if I wanted and whatever else you could want) and then I bought new loom and harness tape and went to town.
It came out AWESOME! I have to try and dig up some pics. It was a lot of work re-wrapping with the harness tape but after I almost quit about 2 times I saved A LOT of money over the new ones. I think I had 200 into the used harness and then the cost of tape, loom and de-greaser. Like I said the hardest part was fighting my laziness, lol.
Sure it will never be as good as the new ones but IMO the money was spent better elsewhere for my car