Hi Steve,
In the early 50's I taught myself and several friends how to fly, with a Firebaby and McCoy 049 diesel engine. We replaced wings and other parts as they broke, or became fuel soaked, but finally wore it out. Always wanted another one, but like you was put off by the prices.
Frank Macy was an honorary life member of our Fireballs club, here in the Portland Oregon area where Jim Walker had his company. Talked to Frank several times about getting an original Firebaby kit, but he only had the plastic fuselage version for sale at the time. There were no full size plans with the original kit if I recall, just an exploded view to help with assembly.
Gil Coughlin was another friend who had a great collection of Firebaby kits and assembled airplanes, that he displayed every year at the Seattle area Model Expo. Here is a link, to the Flying Lines article on both gentleman (Frank is on the left in the picture).
http://flyinglines.org/obit.coughlinmacy.htmlSadly, both are gone now, and I've no idea where one might find any of their kits, or models.
I'd love to see Brodak clone the Firebaby kits, but I seriously doubt there is a big enough market to make that profitable.
Bill