From a publishing industry newsletter called Shelf Awareness:
Scholastic estimated that 8.3 million copies of the 12 million first printing of Harry Potter and the Deathly Hallows sold in the U.S. on Saturday. By contrast, in 2005, some 6.9 million copies of Harry Potter and the Half-Blood Prince sold on the first day.
The New York Times estimated that if the average price per book was $20, "Americans spent nearly $170 million for the book in one day." The AP (via the Seattle Times) calculated that sales of the book averaged more than 300,000 copies per hour or more than 5,000 a minute.
$170 million spent in one day on one book. Wow. I would love to know if anyone will try to estimate other financial effects that Harry Potter might have had on our world. While out and about in NYC this weekend, I kept seeing people reading the book, and wondered if retail sales were down on Sunday because people were holed up trying to finish the 700-page tome. And how much did sales increase on Saturday from the hordes of people there to buy the book? Most booksellers are not making much of a profit on Deathly Hallows itself, as they have to discount it so heavily. Stores were hoping that the extra foot traffic would lead to higher sales on other books-- I only have anecdotal information, but I've heard that certain titles that my company had in promotional displays over the weekend were "wiped out."
Also, how much overtime did the UPS and FedEx workers get? How many people called in sick to work today because they wanted to stay home and read the book, and how much productivity is lost because of that? How much higher were the electricity bills of people who stayed up all night reading? And then there are the endless speculations one could make about J.K. Rowling's net worth, investments, spending, etc.
By any estimate, that's a lot of muggle money.