If you're looking for something fiction, how about "Confessions of a Shopaholic" by Sophie Kinsella? It sounds like the most anti-mustachian book out there, but actually it's about working through the consequences of poor financial decision-making and really depicts the emotional aspects of overspending amazingly well. And Sophie Kinsella's books are very charming and funny. The lead character's learning curve is very steep, which may be more appealing to non-mustachians than non-fiction. At the very least, it would open some good conversations!