The Magic Of Making Up (Get Your Ex Back)
My favorite, really did help my friend and his ex get back together, an he is forever grateful, a little more expensive, but you can put a price on the person you love right?
Get Your Ex Back: The Guide To Winning The Relationship Game (cheap but excellent book)
You want a cheaper option but still high quality. I've done my research and found that people LOVE this book. If anything you should check this one out, only a couple dollars.
How To Get Your Ex Boyfriend Back Using The Law of Attraction
Hey it's using science, it can't be wrong. Joking aside this does actually use some amazing techniques which really work. Would strongly recommend this book for help with your ex