I spent the better part of a year building cables and trying out different designs to isolate the noise, such as having a floating woven metal shield with a small capacitor at one end to ground the shield. I don't remember all the different things I tried, but they definitely had varying levels of material impact. That said, with RCA cables I never got the noise completely out of the system and eventually switched everything out for something with balanced XLR connectors, which eliminated the problem.
tl:dr; expensive cables don't really matter. cable design does to a point, but if you really want great sound without interference, you need to switch to a system with a balanced design. Unfortunately, this requires changing all components, not just the cables.