Found in Waitrose, Nine Elms (near Vauxhall in London)
60 washing pods for £7.
Works out at 11.6p per wash.
By far the cheapest I have ever found these. There are still some in stock in the Nine Elms store.
Currently 60 pods are £10 at sainsbury's, £12 at amazon, £14 at tesco etc...
edit: available online too, thanks emribena