As I just mentioned in the "Classic Cinema" section, Bela Tarr's Werckmeister Harmonies/Damnation set is on sale at amazon.co.uk.

A few others:

Aoyama's Eureka

Tarkovsky's Stalker

Bresson's L'Argent

Ozu's The End of Summer

Godard's Weekend

Sokurov's Russian Ark

[Edit] Sale is now over!