"Getting a spacecraft to land on the moon is both expensive and difficult. To date only three countries, Russia, the U.S. and most recently, China, have done so, and this through government programs.
It's with this daunting task in mind that teams of students and professionals globally began the challenge in 2007 of trying to send a small spacecraft to the surface of the moon and have it, or a deployed rover, travel a distance of no less than 500 meters and return high definition video and imagery."
... "However, as each team has discovered, winning the Google Lunar XPRIZE (GLXP) is an incredibly difficult task. And it's not just the technical challenges they must surmount, their primary problem is finances, or lack thereof."