Didn't John Lewis and Curry's previously stock Kobo's, another two shops to add to the list of those who longer seem to carry any Kobo ereaders.
AFAIK it's only been WH Smith who have stocked the full range for a while now, as weren't they supposed to be Kobo's retail partner in the UK? Which makes it all the stranger why WH Smith hasn't got the H2O, and the only place you can buy it is Argos.