The basic thing you should remember is that copper is a relatively inexpensive material. After all, the penny is made of copper. Silver on the other hand is a fairly expensive material. I have noticed how few high end cables are actually silver. Most of these cables are copper cables with the manufacturer hyping something special about their copper.
Some manufacturers claim better crystal patterns.
Some claim less oxygen. I most cases, these copper wires sell for more money than buying pure silver. Some cables are mixed copper and silver. It is often difficult to determine how much silver and how much copper are in the wires. Stereophile acknowledged that bulk Radio Shack wire sounded good.