I think a 'banner find' is just something that has a uniqueness to it. When I found the old 1930's gumball machine buried underground full of silver war nickles, the nickles themselves only had a combined value of around $5 but people still voted the find to the banner for some reason. I think that reason was because the find embodied the quintessential 'buried treasure'. It didn't matter that the coins themselves were relatively worthless, the find represented a real treasure chest that embodied a feeling that all treasure hunters wish to experience one day - and seeing the box opened for the first time in 70 years made people's imaginations come to life. Like finding an old gun or a gold coin from some well established time in history makes people's imaginations flare and allows them to 'connect' to that distant past time, this is what makes a banner find. For example, a gold coin found in a coin star return slot will probably not make it to banner, but a gold coin found under the dirt of a long abandoned gold-mining town in the old west probably will make banner - because the latter makes a connection to a known past event and can even be traced to individual people (who may have census records as living in that town at the same time as the coin), the gold coin in the change return slot at the coin star does not evoke this same kind of feeling of wonder or strong connection to the past. Just my thoughts on the matter.