I'm totally oblivious to the candy bar 100 Grand.
If it's a Nestle product then shouldn't the promotion/competition have gone something like "If you would like to win a Nestle's 100 Grand" or "to win 100 Grand thanks to Nestle" it would have been a bit clearer. Wouldn't the company have to endorse it's product in a promotion/competition, or sponsor the competition if it's cash?
Another funny thing is I've never heard of a radio station giving away that much money. $5,000 or $10,000 maybe, but never $100,000! (
Not where I come from anyway 
) Any competition with big prize money here is not usually a spontaneous event either. Sometimes the competition can run for a couple of months. I wouldn't think it would be something held in one DJ's work shift?
I don't really know the in's or out's of the business, my point is, I would have been suspicious about the cash prize myself. I probably would have had a laugh at the candy bar and felt a bit stupid for spending that much time and effort listening, so then I would probably demand maybe a cap and a t-shirt as well.