Ridge Street Audio cables were a popular small boutique brand back a few years ago. I have owned many of Robert's cables and cords myself, and yes, they are very good. However, from my understanding, even if Robert is still in business, which I am not sure that he is, he has been laying low for the last few years.
When the proprietor of a small boutique company goes into retirement or hiding, the resale value of their products suffer. It's just the nature of the business. Not that RSAD ever had great re-sale value, but the pieces I have seen for sale lately have been way over-priced. Not for the quality of sound that they deliver, but for their place in the market. After all, the market determines what a product is worth, the market is fickle, and likes to be entertained. When the manufacturer stops entertaining the market, the market shrivels up and eventually dies.
You ad is a good example. Maybe you could have gotten $500 per cord several years ago when RSAD was still actively marketing themselves. Now that they have fallen off the face of the audiophile world, you may only get $600 for both cords. The market has dried up, sorry. I still have a Poiema!!! Signature cord from Robert, and it is a very good cord. I am not currently using it, but I would never consider selling it because I know that I would not get the amount of money in return that the cord's value has to me. I have a pair of interconnects from another small boutique manufacturer that I won't ever sell either, for the same reason.
