The store has a medieval theme to it, with flags and other middle ages-style objects everywhere. The clerks are all sloths who work in different departments. There is one path that is guarded by the Riddle Sphinx. It is also shown to be quite disorganized and mixed up, which Marco quickly complains about on his first visit.
"Trial by Squire" reveals that the store has an "annual Squire Blowout Sale", offering items for squires at a discount.
"Out of Business" reveals that the Quest Buy stockroom is a magical room that turns people's deepest material desires into reality, and if those people stay too long, they will eventually succumb to their desires so much that their "brains turn to goo" and they'll never want to leave.
This might be the reason why all the clerks are sloths.