finding disk brake for my 72 swinger

Brian, you should check Ebay and your local papers for a donor car that has disc brakes on it. There are quite a few around. This way you get all the parts you need for the switchover to your car (upper control arm, spindles, rotors, discs, metering block, brake lines, etc.). I picked up a 1975 Duster off Ebay about a month ago for around a third of the prices you have. Plus, it may have other parts on it you can use, or even sell. Once your done with it call a scrapyard to pick it up and give you $50. Just my opinion. Mike