Could some one explain how to buy best cables?

The above generally is good advice. Except perhaps within a manufacturer's lines of cables, there rarely is a hard and fast correlation between price and quality of a cable--there are giant-killers out there and there are giants too. Your JOR (I was thinking of bidding on that piece myself!) is a good enough piece of equipment that you will benefit from cables that are better than zip cord or the patchcords included with your sources, but the particular sound that suits you (and believe me, EVERY cable degrades the sound to some extent, so they can and do sound different) will depend on your ears and your budget. Try to find a dealer who will let you borrow several wires in your price range and let your ears decide. The Cable Company is pretty good as a source for cable lending, if you don't have a good local dealer. And there are also a number of cable manufacturers who will give money-back trials of their wires, as noted above.

Money and cable quality have nothing to do with each other.
200-300 should get you all you will ever need. There are many on here who do this for an ego stroke, let them piss good money after bad.

In a way I know the answer since in my main system, I had to go thru similar trial and error process about 7-8 years ago. The cables I ended up with and still happy with are NOT the most expensive I tried. Even from similar makes, I ended up with 'cheaper' ones, because they sounded perfect for my system. At the same time the mystique of the most expensive cables from say MIT or Purist audio or Kimber remained. I remember Mr Dunlavy believed in simplistic and inexpensive cable designs. Since I am proponent of Dunlavy Speakers, I tend to believe his theories.

But still, regardless of price, is silver or gold or copper is better owing to the improved conductivity? If say silver is better, than I understand the price since silver does not come cheap. So there has to be some rational...

Just try some Dakiom 203 series stabilizers with the cables you already have... http://www.dakiom.com

I would buy Kimber Kable Hero interconnects and Kimber Kable 8VS speaker cables and forget about it. They are inexpensive, sound good, and your done. That's what I did. Then, upgrades can be elsewhere...or enjoy the music.
John Dean