[Ramrod]

To cook authentic curry from primary ingredients you need to go to an 'indian' supermarket. This is because you are going to need things like Asafoetida, Ghee, Curry leaves etc....unless you are happy doing that you should stick to jars and tins of 'authentic' curry paste like cjll3 mentioned. If you go to a good bookshop you will find lots of cookbooks devoted to curry.