The entire event of auctioning was put on Chang Bo's shoulders, and Xie Mei was just there accompanying him as a 17-year-old beauty who just had the job of announcing the item name and bidding amount.
Even though she had mastered and even created a new fighting style using firearms, she wasn't as knowledgeable about firearms as Chang Bo. Well, at the very least, Mark thinks so. Hence, she was just there to please the audience with her presence, that's all. After all, the nobles and wealthy individuals who came from far away wouldn't want a male to be the host.
Chang Bo was doing it for the money as he would get 1000 gold coins as his remuneration and Xie Mei was doing it as Mark promised her this thing called a 'date', where both of them spent their time alone and he would accompany her anywhere she wanted to go.
The motivation was there but there was also this nervousness as neither of them ever handled an auction before.