http://www.prescriptiondiet.com/zSkin_2/index.jsp?PRODUCT%3C%3Eprd_id=845524441760430&FOLDER%3C%3Efolder_id=1408474395181164&bmUID=1135969218262&bmLocale=en_GB Hills don't sell direct to the public as far as I know, only through retail outlets, vet practices and dog shows (or through their breeders' scheme but that requires bulk buying) If you scroll down the page you'll find the Nature's Best range.
Pets at Home sell the product as well as the JWB range and you can order any of their stock on-line but if you want to buy a large brand such as either of these then Google for price comparisons - savings can be quite substantial and you may find you have a local feed store which can obtain products more cheaply than you (because it cuts out your delivery charges).
There are many food topics on the forum so worthwhile using the "search" facility - these more than adequately cover opinions on a multitude of diets.
regards, Teri :)