Home made curry

well I decided I wanted a curry so out came the cook books. Lamb Biryani was what I wanted to try but reading the recipe I was one or two ingredients short.....why is it Im always short of something ? Curried ginger lime leaves, or saffron flavoured curry powder ? Im sure the people who write the books are in cahoots with the spice manufacturers. In the end I used a basic recipe for a north Indian Chicken Curry, even made my own Roti.....surprisingly easy....