Another point I forgot to mention is what quality and size you'll deal with. OP mentions "gaylords full of scrap insulated wires, anywhere from thin 20 gauge to 1.0 gauge, it is just a mix of all of these". Size matters for reselling the clean berry copper, but also if you need to adjust your stripper all the time. If you need to sort your wires by size first and/or readjust your stripper all the time is time-consuming on the long run (time = money). Also, with smaller gauge, it takes more time to get the same volume/weight a larger wire does.