I used in high school and college "The Practice of Harmony" by Peter Spencer. The book is extremely thorough. It's in the standard language of theory. That is, it's the basis for how we talk about theory. I use it with some of my students when I feel their instrument practice is coming along.
The book is based on the rules set down by J.S. Bach after studying a large number of his chorales. So the practice in the book is mostly for four part vocal writing, but it's the same for everything, of course. The book is in textbook format, so each chapter explains the theory of the chapter, and then there are numerous practice problems for the rest of it. You can find this book used at Amazon.com; my students say they are around $15-20 there.
Another book to have for learning chord symbols is "The Jazz Language" by Dan Hearle. It's a thin book, at 64 pages, so it's under 20 new. It goes through practically all chords used in jazz (the same chords are in gospel, and ALL genres of music, jazz is just more complex). It's also a good basis to start learning improvisation.
Both these books are best used together, to really understand harmony in this genre of music.
Nick