The first UK price looks like around £999 from Nevada who expect stocks spring/summer 2015. This is more than I was expecting.
This image is the best I could find. The image is located on the Universal Radio site in Ohio and the link to the image will be removed if this is a problem.
I would consider investing in this transceiver, but would be looking for a better price. The FT450D is currently £699 in the UK (even less at MLS £619.95 according to G1KQH) I wonder if they will spin out an FT817 replacement based on the FT991 design? I am sure there would be a good market for a 5-10W version here in the UK.