Sell something people want to buy. Easier said than done.
What if selling something everyone is familiar with isn't the way to go? What if you made your niche even smaller? Because if the internet and state fairs have taught us anything, it's that there's no such thing as your niche being too small. Narrow your focus so much that you are reaching out to a very specific audience. Would you rather have 100 people stop by your booth, but nobody buys? Or have only ten people stop by, but all ten buy? Don't worry too much about your traffic. Instead, focus on the value you are bringing to the small group of people you already serve.