Or
Magic Shop dotcodotuk which I use for almost all my book purchases.
World Magic Shop is ok, not bought anything off it yet but free P&P on any order, makes the prices good. And
Magic Tricks dotcodotuk is ok, I bought a few things off there. They're amazing at delivery, I ordered some stuff Wednesday afternoon and had it through my door Thursday morning.
I don't see how sticking with penguin's going to be the cheapest option for us Brits? The prices are good cause of the strong pound, granted, but shipping, potentially getting charged more by customs, plus I don't exactly mind paying a whole pound more if I get my product in about three days, rather than at least three weeks. By the time you add in all the factors Penguin's just the same price as everywhere else, only with a massive wait.