Quick Profit (15 cents)

So, I am roaming around this used book store and, for some reason, pick up a book about Georgian architecture in London, a book that I had no interest in although I am sure that it is a fine piece of scholarship, and I open it up and sense that there is something sort of thick between some pages towards the middle and look to see what it is and find 8 $20 bills. The book cost me $4. My profit was $156.00.