I would like to nominate "The Dark is Rising" by Susan Cooper. It is the second in a series, but it is supposed to be a stand-alone and seems to be better liked than the first in the series. I've found available for purchase in epub in several stores (Borders, Kobo), but I'm not sure if Amazon sells it as a Kindle book as well. Kobo seems to have the cheapest copy:
http://www.kobobooks.com/ebook/The-D...FAg/page1.html