Cable recommendations for my new (preowned) system...

The Cable Company has a used cable site. Most cables are 50%.

Given your equipment I would recommend all copper which would not overly highlight the treble and generally be a little warmer. I would not spend a lot of money… say less than $50 per set. At the cost level if you spend too much the investment would be better spent on component upgrades. As your system changes the resolution increases and the greater the difference interconnects and cables become.

Typically:

copper is warmest
silver coated copper intermediate 
all silver very detailed but will highlight any flaws in components

When I had a modest system I bought some real high end cables. They sounded terrible… passed along all of the signal. Twenty years later I pulled them out and tried them out on my vastly superior system. They sounded fantastic! Be careful not to get ahead of yourself.