Best Buy has marked down several horror movies for the holiday. I picked up Nightbreed for $6.99 and Kubrick's The Shining for $7.99 yesterday. I don't know how long the sale lasts.
WalMart also has a section of spooky movies on sale for Halloween, including 976-EVIL, Swamp Thing, Interview With A Vampire, and others including family and kid's selections. I think these are on sale for the whole month.
Anyone know of any other bargains?