If you can't find a 117/317, you could probably get by with a fixed voltage regulator like the 7805 (can't seem to locate a 3V version (which would be 7803)) and 2 or 3 diodes in series on the output to drop about 2 of the 5 volt... The 78xx regulators just want caps on input and output, nothiing else.

Ten years, or so, I had a portable CD-player in my car. The entire content of the cig. adapter plug was a fuse and 7 1N4001 diodes in series...

/Michael