I am planning on buying books about how to grow your own bonsai, but just a quick and relatively stupid question...can you grow a bonsai from any seed purchased from a nursery?

Bonsai are usually trees, or wood shrubs, however you can grow some neat bonsai with woody herbs like rosemary and thyme. You can't usually get tree seeds from a nursery, and rosemary and thyme are available as plants. Rosemary is actually a pretty good one to start with, because it grows pretty fast, prunes easily and is pretty forgiving, not like a woody bonsai, that once you cut off a branch, it won't grow back if you have made a mistake. Rosemary will just grow another one. It will make a pretty credible bonsai in just a few years, where as it can take ten years or more to grow a woody one. A good book is Bonsai Life Histories by Martin Treasure, it is about bonsai he has grown, and contains a lot of good tips and short-cuts about growing them as well as a step by step how-to, and coming up with really good bonsai in a relatively short time.