The reasons for the faked moon landings:

Cold War prestige — The U.S. government considered it vital that the U.S. win the space race 

against the Soviet Union. Going to the Moon was risky and expensive (John F. Kennedy famously said that the U.S. chose to go because it was hard).

Despite close monitoring by the Soviet Union, Bill Kaysing maintains 

that it would have been easier for the U.S. to fake it, and consequently guarantee success, than

 for the U.S. actually to go. 

Money — NASA raised approximately $30 billion to go to the Moon. Bill Kaysing claims that this

 amount could have been used to pay off a large number of people, providing significant motivation

 for complicity .

Risk — This argument assumes that the problems early in the space program were insurmountable, even by a technology team fully motivated and funded to fix the problems. Kaysing claimed that  the chance of a successful landing on the moon was calculated to be 0.017%.

Distraction — According to hoax proponents, the U.S. government benefited from a popular

 distraction from the Vietnam war. Lunar activities suddenly stopped, with planned missions 

cancelled, around the same time that the U.S. ceased its involvement in the Vietnam War.

 (However, the Apollo program was cancelled several years before the Vietnam War ended.

Delivering the promise — To seemingly fulfill President Kennedy's 1961 promise "to achieving

 the goal, before this decade is out, of landing a man on the Moon and returning him safely to

 the Earth." 

Here the cheap studio before they took the landing:

http://en.wikipedia.org/wiki/File:Apollo11C.jpg

Photo of the high-quality SSTV image before the scan conversion

And here how it looked later:

http://en.wikipedia.org/wiki/File:Apollo11D.jpg

See here how Rammstein imagines the moon landing: