I have 2 Universal carbines and a GI. One of the Universals is a .256 Winchester Magnum, called a Ferret, and is a collector's item. The ordinary GI clone Universal is like the others say, not a collector's item really. HOWEVER, the Universal and maybe the other clones have one feature that is worth thinking about. The bullet feed ramp is twice as long as on a GI carbine, and will feed soft nose bullets perfectly. I have Rambo'd many 30-rd mags through mine as fast as I could pull the trigger. The GI would frequently fail to feed the soft nose rounds. It used to be nearly impossible to buy FMJ carbine bullets, so I reloaded thousands of soft nose bullets, and the Universal was the only carbine that would reliably feed them. If I saw ANY brand of carbine clone in ANY condition at a gun show cheap I would buy it without hesitation. You can always fix and replace anything wrong except an AFU receiver...
Numrich Arms bought up all the remaining Universal/Plainfield/Iver Johnson parts when that merger-mess went out of business. The remaining stock of Universal parts is at:
www.e-gunparts.com/products.asp?chrMasterModel=3830zCARBINE
and
www.e-gunparts.com/products.asp?chrMasterModel=3830zMISCELLANEOUS