Whoever wins the White House this year will be ferried to Camp David and elsewhere by the most advanced presidential helicopters ever developed. The helicopter also will be the most expensive, stung by skyrocketing development costs from the start.

More bad news came this past week, when a top Pentagon official said the price tag for the VH-71 aircraft has now reached $7.5 billion — significantly more than the $4.5 billion original estimate. And, given the amount of testing and rejiggering still ahead, it would be safe to bet the cost will soar some more before the Marine One copter itself finally does.

Lockheed Martin Corp. calls the VH-71 an “Oval Office in the sky,” an aircraft packed with super-sophisticated communications systems, extraordinary safety and defensive measures, advanced cockpit controls and space for more passengers.

The helicopter is slated to be ready by 2010.

Another “CSI” canard debunked: Gun experts with the National Academy of Sciences’ National Research Council say in a new report that the presumption that every gun leaves telltale and unique marks on bullets and cartridge cases has not been fully proven scientifically.

That means a proposed U.S. Department of Justice database containing images of the tool marks from all 4.5 million guns sold in the United States each year would do little to fight crime, given the current state of technology. Until it can be proved that the microscopic marks are unique to each weapon and remain unchanged over repeated firings, a database search would yield too many matches to produce a usable list of suspects.

The redesigned $5 bill debuts Thursday (March 13), and the first to enter circulation will be spent at the gift shop at Abe Lincoln’s recently restored cottage now open to the public in northwest Washington. (Lincoln’s image, of course, appears on fivers.) Located on the high ground of what is now the Armed Forces Retirement Home, the nine-room structure served as a retreat for Lincoln when the weight of the war, the death of his son and stifling downtown summers became too much to bear. His last visit was the day before he was assassinated.

Little-known fact: One of the last official acts Lincoln performed on the day he was shot was to put the U.S. Secret Service in charge of fighting currency counterfeiting.

Now there’s a place to vent when airport security rigamarole makes you pull out your hair (but only after you’ve removed your shoes … ): The Transportation Security Administration’s new blog site — www.tsa.gov/blog/ — has become a receptacle of hundreds of complaints, questions and observations, including some that have triggered a change in TSA policy. Apparently, the agency’s powers-that-be actually read the comments with the intent of improving operations.

Best recent comment, from an anonymous poster: “I’m just glad (attempted shoe bomber) Richard Reid didn’t try to hide a bomb in his under shorts.”

Some of the best of the 1,000 broadcasts that put the Great Communicator on the political road to the presidency will begin airing next month on radio stations across the country. The Ronald Reagan Presidential Library has assembled 30 of Reagan’s five-minute commentaries on the economy, immigration, taxes, abortion and other issues that aired from 1975 to 1979. The purpose, library officials said, is to “reach the several generations of Americans who never heard him speak.”

(E-mail Lisa Hoffman at hoffmanl(at)shns.com. SHNS correspondent Lee Bowman contributed to this column.)