Feasibility of Moon base ?

NASA's evolving plans for building a permanent moon base by 2024 portray the facility as a scientific outpost where astronauts will build telescopes, forage for rare minerals and prepare for future Mars missions to be launched from the lunar surface.

It is expected to cost 200$ billions over the next 20 years.
The researchers with the most to gain from a permanent moon outpost are experts in lunar geology, who see a chance to finally glimpse the moon's full history, including details of how it is thought to have formed from a Mars-sized planet's collision with Earth more than 4 billion years ago.

What supporters and opponents of a moon base fear most is a repeat of the International Space Station, widely considered one of NASA's worst failures. That facility has not delivered on promised research benefits and brought few inspiring images of exploration from its perch in low Earth orbit.

Some boosters of the new moon missions argue that helium-3, an isotope rare on Earth but common on the moon's surface, could be used to fuel nuclear fusion reactors on Earth. But no one knows if reactors based on helium-3 would be technically or economically feasible.
Even if the moon were made of solid gold, it's doubtful that exporting lunar resources to Earth would be profitable. Manned missions using the space shuttle cost about $10,000 per pound of payload--about the price of a pound of gold.

"Sometime in [the] next 100 years we may have the construction base on the moon to do this, but in the near term it makes no sense," said Lawrence Krauss, a physicist at Case Western Reserve University who supports building a human presence on the moon over the long term.

Source:
http://www.chicagotribune.com/news/nationworld/chi-0701070361jan07,1,2314395.story?coll=chi-newsnationworld-hed&ctrack=1&cset=true
All said, moon base will be a next major step for mankind in exploring the cosmos.