Wonderful Intro to Field Theory
There is an enormous gap in books covering quantum theory between the popular expositions and the advanced texts which are generally impossible to read unless you are an expert. This book is a wonderful bridge between these two extremes and if you can go through it you will at least have a shot at the more advanced books. The only problem I think with this book is that the author tries to cover too much ground and as a result very few topics are really covered thoroughly. Nevertheless, the coverage of the path integral method alone may be worth the price of admission, and the propagator method also receives good coverage.