They'll probably sell the first 20 or so seats at that fare, subject to 200 quid "taxes" of course! After that the price will progressively rise to the point where you won't pay that much less than on a full service carrier. RYR haven't yet managed to entice me onto one of their European flights, and I think Hell will freeze over before you will find me on one of their transatalantic flights. Nevertheless I have no doubt that there will be plenty of naieve takers.