UK website Rarewaves has the 4K disc for $16.99 plus $4.81 shipping to the US.
https://www.rarewaves.com/products/5035673000021-the-seventh-seal-4k-ultra-hd-blu-ray?variant=39614783389793
Just received my copy and played a few scenes. The picture quality looks excellent with nice looking blacks and a very sharp image. Have seen this movie many times and in different formats and this looks the best.
Website Dvdcompare has a review of the UK 4K release. Chances are good Criterion will release it in 4K so i might skip this one.
https://www.dvdcompare.net/review.php?rid=6777
Here are the extras that will be on the disc. Website Zavvi has it for $28 plus shipping.
4K (2160p) UHD Blu-ray presentation in Dolby Vision (HDR10 compatible) (Region ABC)
High Definition Blu-ray (Region B)
Newly recorded audio commentary on The Seventh Seal by film critic and...
On October 18th BFI will release The Seventh Seal on 4K disc. This will be the BFI's first 4k disc and the info on the extras will be available at a later date. One of my favorite Bergman films and one wonders if Criterion might also release this on 4K?