Your options for replacement are limited by the selection at the local home improvement store. You can install just about any light fixture. Keep them fairly small & light weight, not of chandelier proportions. Use longer wood screws in the holes that would connect the fixture to the electrical box of the home. You can buy 12 volt
bulbs in the standard 120volt AC style at NAPA. They're used in some 12Volt DC lead lights. Just remember this when you go change bulbs in the future. I wrote this on the fixture itself with a magic marker.