When Gu Xijiu traveled with Yun Yanli, they would often visit auction houses to see if they could acquire any notable items of value. More often than not, Gu Xijiu was able to find the Youth-Retaining Herb at a fairly reasonable price- a class-three spiritual stone for a finely-graded herb.
She used to find the Youth-Retaining Herb almost every time she visited an auction house, but as she was not interested in preserving her youthful looks back then, she was not very keen on acquiring the herb.
Yun Yanli wanted to buy the herbs for her, but she turned him down. She would have reconsidered his offer, if only she knew about the use of the herb earlier. Now that she desperately needed one, it was nowhere to be found. Why did the herb go out of stock all of a sudden?