If you know what you're doing, there's no question that AdWords are worth every red cent you spend on them.
However, the big word is "IF" and simply having the money to throw at AdWords is a long, long way from making you sufficiently knowledgable.
So start by spending a few dollars on what you can learn from the likes of Perry Marshall -- see
http://www.perrymarshall.com/google/
"A fool and his money are soon parted" is an old saying, but it certainly applies to AdWords -- or any form of advertising for that matter!
Duncan