You can simply squeeze a pomegranate for fresh juice in your juicer. If that's too much trouble a good quality unsweetened pomegranate juice like Pom Wonderful will work.
Pomegranate molasses and orange blossom water are pretty easy to find in a grocery with a good international foods section. Look in the middle eastern area. If you can't find it in your local grocery look for it in a middle eastern grocery or international grocer.