I recommend Griffiths, it's very readable. If you need cheap, search the online stores for a second hand paperback, or talk about acquisitions with your librarian. Or if your situation is really extreme, perhaps write to the author for blessing to just download it in djvu form from somewhere with weak intellectual protectionism law. My point is that in the long run we're probably all better off with you getting a well-recognised modern textbook rather than trying to make do with perhaps worse information.