If anybody is interested in a great deal...
Amazon has The Kingdom 1 & 2 DVD set
for $11.49. I'm pretty sure it's only a Cyber Monday "boxset" deal (it's listed in that section at least) – and doubt the price will stay that low for too long.
I already have the R2 (PAL) 4-DVD Set, but I went ahead and ordered this, since I friggin' love the series so much.