Best-selling author and black-arts enthusiast J. K. Rowling is said to be apparating into the East End this summer. Word spread among brokers weeks ago that a famous British writer, who turned out to be the megamillionaire Muggle, was looking for a “very private” getaway big enough for her family of five and that she was willing to pay as much as $500,000 for July and August (or, pulled from a vault at the goblin bank Gringotts, the equivalent in gold galleons and bronze knuts). Rowling, who was broke and on welfare when she sold the first Harry Potter book and is now one of the richest women in England, got a deal nonetheless: According to a real-estate source, she’s only spending half of that for a place in Bridgehampton. Perhaps she’ll use the time to finish off the seventh and final novel in the series. Publicists at Scholastic Books had no comment on the author’s personal life or the release date of the next Potter.