The United States government is buying enough of a new smallpox medicine to treat two million people in the event of a bioterrorism attack, and took delivery of the first shipment of it last week. But the purchase has set off a debate about the lucrative contract, with some experts saying the government is buying too much of the drug at too high a price. A small company, Siga Technologies, developed the drug in recent years. Whether the $463 million order is a boondoggle or a bargain depends on which expert is talking. The deal will transform the finances of...