The looking glass monocles were among the first items in the NEX cash shop, and the centerpiece of the infamous Monoclegate crisis, in June 2011.
It was the (right/gold) version of the monocle that was for sale in the NEX shop.
Of the (left/gold) version, apparently 8 copies have entered the game. Four were given as prizes in Somer Blink lotteries around EVE Vegas in September 2013, and four more were dropped as loot in dev events around the same time.
The (left/gold) monocle is worth well over 100 bn isk. The (right/cold) monocle did not sell well originally, but has increased in price to over 5 bn isk since it was removed from the shop in June 2014 when it became the NES shop.