Amazon.co.uk offers The Coen Brothers Collection on Blu-ray Disc for $10.70 (£7). At checkout, it drops to $8.91 (£5.83). With $4.71 (£3.08) for shipping, that's $8 under the best price we could find at Amazon on this side of the pond, and it's $18 under the lowest total price we could find elsewhere. It includes A Serious Man, The Big Lebowski, Barton Fink, Burn After Reading, and Intolerable Cruelty.
Of note, although the movies themselves will play on US Blu-ray players, the extras and special features may not.