The price is not low because of supply and demand, but because it is not a very useful list. When you pay a lot for a list it is because it has been curated and you are buying a list with X user having Y attribute[s]. Y='Facebook user' here, that is hardly worth anything. The network is too large for it to be significant for any real marketing campaign. Essentially you have a list of 1,000,000 VERY loosely related users.
I was considering the possibility of selling these emails to a spam email list, but then realized that since so many accounts' email addresses were changed to FOO@facebook.com, the value of these 1MM facebook accounts has diminished rather significantly in this regard.
