In my experience with power cables, if you do notice a difference, the one you were previously using has some kind of fault with it.
I've personally seen noise issues vanish by using a proper cable, but never heard a difference going from good to expensive.
I only own one fancy power cable, and it's an XLO with Furutech connectors (rhodium plated, if I remember correctly).
It's a really high quality cable, nice and sturdy, but there's no audible difference between it and any of my good cables.
It did however make the hum go away when I switched from the included cable on my Xindak amplifier (which is why I bought it in the first place).
What you can do though, is that many of the DIY-type power cables don't require soldering, so anyone can make the exact length they need.
Many will also last longer than the cheap molded cables, and look cooler, so IMHO it really comes down to how important those things are to you.
If you're fine with a lot of tangled up bland, black cable hanging from the back of your equipment, and you have no noise issues what so ever, I'd say save your money.
I'm sure some people will just claim I haven't spent enough money yet, either on the cables themselves or the equipment, but at that point you really have to start asking yourself what their agenda is.
Because of my tinnitus I've had my hearing tested several times, and it's still way above average.