I had neighbors years ago who must have spent $10,000 on fireworks. They would shoot off aerials and roman candles for hours on the 4th. Fortunately they never started a fire, though one kid shot roman candles onto a neighbor’s roof. I was glad when they moved. They had to have gotten fireworks somewhere cheap because if they bought all those at a stand it would have been thousands.
Always buy fireworks from reputable dealers.
I have found that the guy missing two fingers and wearing an eye patch always seems to have the best selection.
Maybe they owned the stand and firing off the unsold items.