Braun Oral B Professional Care 600 Design Edition Electric Toothbrush+ Travel Case @ ASDA Instore for £12.50
They've got at least 3 packs left at ASDA Crossharbour/Isle of Dogs when I bought mine.
Only drawback (for me) is the pink colour.
However, the missus loved it!
Not too sure if national, just might be as I remember another member getting it for a tenner at his local asda!
EDIT: Price is £12.50