There doesn't appear to be a poll, but I would say I was a RP supporter in 2008, even before I fully understood the ins and outs of libertarianism, in a sense. I do know that I didn't really like Obama or McCain, and looked at RP with some interest, but I never realized he had such a devoted following. So RP was more like a "passing interest" for me. Now since I have done my research, I have concluded that supporting Paul is definitely worth it.
I did recognize that both parties were corrupt from an early point in my "political awakening" in a sense... I remember having many lively debates with my partisan dad about how evil both parties were, but I guess I had given up hope in anything actually changing.