Hi, being the T-5 co-registrar and First Mustang Club of Germany editor, you may want to check our T-5 website at
http://people.freenet.de/fmcog
(in the menu T-5)
Early T-5 emblems have become obsolete since years, although occasionally there is one on e-bay.
I haven't found one in the past 3 years and have requests of half a dozen of owners. They typically now fall into the 75$ area, although 150$ have been offered recently.
Wolfgang