I wanted to bump this thread because as of this writing, Amazon has slashed the price of the 4K edition to $9.99. I don't know how long this sale will last but thought it would be worth posting here in case anyone is interested.
There has been no corresponding price drop for the Blu-ray...
According to the cover images, the 4K copy does not include a 4k Blu-ray to be backwards compatible. That is unusual, especially for a brand new film. This setup wouldn't allow current Blu-ray users to future proof without making two purchases.