GG,
If you are not opposed to starting off with a die-cast, I believe that JADA makes a 1/24 scale International roll-back. Most die-cast and Internet retailers have them for about $35. There was a company that used to offer 1/24-1/25 scale wreckers and rollbacks about 5 years ago, but I can't recall the name. I want to say Rick's or something like that. I am at work right now, so don't have access to my files. If you can PM me, I can try to locate it for you. You might also try asking over at Yahoo's Model Truck Discussions. Good luck.
David