I agree that cables can make a huge difference. Especially, high quality, quiet power cables. Plus, I agree price does not necessarily mean better sound. I'm not in a position to compare super expensive cables (plus, my system does not merit such high priced cables). Plus, sound characteristics is such a personal taste thing for the buyer.
I think as long as you have a well built, quality, quiet cable...you are set. Then as you want to fine tune, you can steer your cable choices to meet more taste preferences.
Since moving to my new listening room where I have free reign (unlike the previous living room), room treatments have become the biggest "bang for the buck" improvement.