Looks like the 4K box set of The Ladykillers is getting harder to find. You can still pre-order it on Diabolik but not sure they might get them and will wait until i see it in stock.
Noticed one website that has reviewed the 4K release of The Ladykillers and the reviewer says " As a 4K UHD set the package is amazing; the native 4K picture has had a terrific clean up, is bright, extremely well detailed and shows a depth of colour never seen before". At over $50 i might buy it before it's sold out.