Where can i find a book thats now stopped being published?

My son has heard a story about a bogwoppit at scouts and he loved it. i went to waterstones to buy it for him but was informed it has stopped being published i think they used the term, "out of print" i have tried ebay, local book shops and charity shops with no luck does anyone have any other ideas about where i can find a copy? many thanks
Answer
I have listed a couple of links below for you that should let you get hold of your book. happy hunting.