Two of the best horror flicks in recent years are dirt cheap right now, and you really should grab them while the grabbing is cheap.
Trollhunter- $7.99 I Saw the Devil- $9.99
Click the pics below to grab them from Amazon, or head over to to Best Buy and try your luck there; they have them at these prices too, but whether or not they're in stock is a YMMV (your mileage may vary) thing.
Deals seldom get better than this. so don't sleep!