Are there any good introductory electromagnetism books that don't cost too much? I'm interested in relatvity but I would like to back up and gain a more solid foundation in electromagnetism first. I would like something modern, somewhat rigourous(mathematically), and preferably with a conversational tone. I would also be nice if it convered electromagnetism within special relativity, and it's invariance. At this point i know very little elctromagnetism beyond, potential, superposition and gauss's law. Yes i do know vector calculus. thank you.