Amazon's current Blu-ray Boxed Set of the Week is for the 4-movie set
Ray Harryhausen Collection (comprised of
It Came From Beneath the Sea, Earth vs. the Flying Saucers, 20 Million Miles to Earth and
The 7th Voyage of Sinbad), which which can now be had for only $49.99 (54% off, or about $12.50 per movie). The price tracker shows that this is the lowest this compilation has been. This offer is valid through October 2.
Thanks to forum member "Nightman04."