(Corrects to make clear re-use of rockets is still being developed)

* Firms owned by Elon Musk and Jeff Bezos vie for Florida complex

* Delay costing NASA $100,000 a month

By Irene Klotz

CAPE CANAVERAL, Fla., Oct 1 (Reuters) - Four decades ago, NASA's Launch Complex 39A was at the center of the Cold War race to the moon.

Now the mothballed launchpad at the Kennedy Space Center in Florida, which dispatched Neil Armstrong and his crew on their historic Apollo 11 mission in 1969, is the focus of a battle of another sort, between two billionaire techies seeking to dominate a new era of private space flight.

NASA had hoped to turn over maintenance of the pad to a private company by Oct. 1, saving itself $100,000 a month in maintenance costs, according to NASA spokeswoman Tracy Young.

Instead, fierce competition for control of the pad by digital entrepreneurs Elon Musk and Jeff Bezos has led to a government probe and congressional lobbying, delaying NASA's choice of a partner.

Musk's 11-year-old Space Exploration Technologies, known as SpaceX, already has two U.S. launch sites for its Falcon rockets at Florida's Cape Canaveral Air Force Station and California's Vandenberg Air Force bases.

Musk, the co-founder of Paypal and chief executive of electric car maker Tesla Motors Inc, also plans to build a site, probably in Texas, for commercial launches and wants Pad 39A for Falcon rocket launches to ferry cargo and possibly astronauts to the International Space Station for NASA.

Blue Origin, the company formed in 2000 by Amazon.com Inc. founder Bezos, is working on a suborbital reusable spaceship called New Shepard. A smaller test vehicle made a debut flight in 2006 from a company-owned site in west Texas. A second test vehicle flew in 2011.

Last October, Blue Origin tested a crew capsule developed in part with NASA funding.

Two weeks ago, Blue Origin, based in Kent, Washington, filed a protest with the U.S. Government Accountability Office over the NASA solicitation for Pad 39A proposals. The GAO is scheduled to rule on the dispute by Dec. 12.

SpaceX told NASA it had no problem with other companies using the launchpad if SpaceX was awarded a five-year lease. However, Musk says SpaceX is light-years ahead of the competition.

"I think it's kind of moot whether or not SpaceX gets exclusive or non-exclusive rights for the next five years. I don't see anyone else using that pad for the next five years," Musk told Reuters.

"I think it's a bit silly because Blue Origin hasn't even done a suborbital flight to space, let alone an orbital one. If one were to extrapolate their progress, they might reach orbit in five years, but that seems unlikely," he said.