Here are a couple cheaper 5 lug swaps. They aren't a big break kit but the calipers aren't bad. Might be a decent start and then upgrade later. I would have to use moser axles and not those but everything else would work.
http://www.ebay.com/itm/OE-MUSTANG-5...6688db&vxp=mtr
http://www.ebay.com/itm/FORD-MUSTANG...b29a1b&vxp=mtr