Trading Up: The New American Luxury - by Michael Silverstein and Neil Fiske
i read this book with fascination as it is very important for the Silicon Valley 100 (an influence marketing company).
this is a well-written book filled with examples of how consumers "trade up" -- essentially opt for luxury items for things they feel passionate about. that might be a $4 coffee from Starbucks, a $40 bra from Victoria Secret, a $4000 set of clubs from Callaway, or a $40,000 car from BMW.
Summation: if you are in marketing or product development, this is a book worth reading (and is a really fast read).