I don't find it so unbelievable that some audiophiles would spend money on tweaks like "brilliant pebbles" that so clearly defy common sense. As a newcomer to the hobby, I regarded claims of power cords influencing a system's sound quality as nonsense, but eventually discovered that a $10 Volex actually DID sound much better than the stock cord on my CDP. When I told my non-audiophile but somewhat technologically savvy and music-loving friend he thought my mind was playing tricks on me until I A/B'd the cables for him; after doing so he confirmed the Volex made the CDP sound much better. It makes no sense to me, but I've heard it.
Personally, I wouldn't buy a much more expensive cable than the Volex for my system, but knowing that power cables do in fact influence a system's sound I can no longer be so sure that speaker cable doesn't matter, or ICs are all the same, or even that a more expensive power cord would not be "worth" the extra money. There are people that believe common sense and science suggest that all CDPs, amps, and cables ought to sound the same if designed properly - a lot of audiophiles would say that their own experience contradicts this belief. Is believing that a bag of rocks will improve your system's performance really such a ludicrous suspension of common sense when? Maybe, maybe not, however, I know I wouldn't spend MY money to find out.