It's indeed the US release with region A blu-ray. The prices you see on the US Zavvi page are for customers outside the US. You can also order it from Zavvi uk for 50 £ (or the German Zavvi). It's not unusual, for example some US Blue Underground releases also pop up on Zavvi, but also at ridiculous prices.
If you want such US editions outside the US (and I certainly will check out those Criterion releases) you can go cheaper with amazon.com, DeepDiscount or DiabolikDVD.
Blue Underground USA Blu-ray releases should also not be listed on Zavvi UK as they are not BBFC certified
It's OK for them be listed on Zavvi USA or on another USA retailer website
Zavvi USA is now separate from the other Zavvi websites
Zavvi USA can sell USA and UK Blu-ray releases
BBFC Website
The Video Recordings Act 1984 (VRA) makes it illegal to supply any video, DVD or Blu-ray
in the UK which is not classified by the BBFC
Find out more about the BBFC and the work we do; parents guides, age ratings, how and why we classify content.
www.bbfc.co.uk
Reason why you don't see Arrow Video
USA only releases as (in release that did not get a UK release from Arrow) on Zavvi UK is they not BBFC certified
Arrow Video USA release of Django for example was removed from Zavvi UK website for that reason but is listed on Zavvi USA
There are other Arrow USA only releases you will see listed on Zavvi USA but won't see listed on Zavvi UK
Zavvi don't have third party sellers use their UK website to sell blu-ray like Amazon UK do
USA imports on Amazon UK are third party or Amazon USA
Amazon Sarl UK/EU are not the seller of USA imports on Amazon UK that's the difference
Retailers Music is allowed be sold regardless what country it's from most times
With odd exception where a music release has a restriction on what country a retailer can ship to
Example Waxwork Records The Fog and Escape from New York was USA shipping only due to Silva Screen Records having rights outside USA