Alcoholics Anonymous Collectors' Items

Since I've started surfing around eBay in earnest, I am quite amazed at the range of items which are collectible - for instance, early editions of books from Alcoholics Anonymous fetch some quite high prices when they're in great condition. This could be a great niche market to explore to earn extra income - I suspect there are a lot of people who, like me, have never given a thought to this niche market.