You are correct about what merchandising is.... I'll let others tell you more about it as I don't do it. However, "decent" money is a subjective term. Some folks are happy to work for $10 an hour. Some demand more.
It sounds (from your posts) that you are looking to maximize your income doing this part time. That's exactly what I do. Allow me to ask: What do you consider "Decent" money and what is your income goal? How many days on a weekly/monthly basis do you plan to shop?