This is the USB stick type walkman.
Sainsburys have been clearing the Walkman range NWD-B103 and NWZ-S515, discounting them to 9.99, one model at a time. The S515 video model in white was mentioned here about three weeks ago, and the same in black reduced to 9.99 about a week ago. The NWD-B103 - white model only - reduced a few days ago, my local store has one left today. The same in black remains at 24.99 but seems likely will also go to 9.99 at some point. So if you are unlucky on the white model keep a look out and the black one will probably be along soon!