2-Channel System
Speakers ------------- 36%
Amp ----------------- 25%
Source --------------- 30%
Cables --------------- 9%
I generally agree that speakers are one of the most important components of an audio system, but only because they are so subjective and it really is a matter of personal choice. That doesn't necessarily mean that I think you should spend the most on the speakers... just don't short change yourself.
I may be one of the few, but I also believe that the source is also one of the most important components you can buy, and maybe even the single most important. I would spend more on the source than many other folks would think prudent. If you start out with garbage (noise, distortion, lack of clarity or transparency, no soundstage, etc.) it can't be made better by good electronics or a fantastic pair of speakers. Amps, preamps, cables, and speakers can only try to reproduce the signal they are given, and typically succeed in degrading the signal to some degree... with some electronics and/or speakers making it significantly worse!
Start with the best source(s) you can afford, and a pair of speakers that you like the sound of... everything in between should be carefully selected to provide balance and to work in harmony with the beginning and the end of the signal chain; but spend more at the two ends. That's my opinion, anyway.