I have just applied the other day for an Amazon fire 4 series, 55in 4k. tv for £150 for Prime members, I think it is normally £550.
It is by invitation for new and existing Prime members on a limited number of tv’s (no mention of how many) and applicants will be notified between November the 22nd and the 25th, with an 8 hour window to order it, if they have been chosen. I will let you know if I have been lucky.