Transparent Cables

I am not an audio guy, but I was given a pair of Transparent Cables to sell for a friend (Balanced Musi Link Ultra 1MPR KU3) and before I post them for sale I wanted to get an idea what to ask moneywise. They appear to be new in the box but there is no paperwork or instruction manual with them. Anyone have an idea what a fair asking price should be?
I'm seeing that other Transparent Cables are selling for extremely high prices. What makes these so valuable?