I went by popsike's own FAQ. Under "What Is Included", they write, "auctions of rare vinyl records sold for around 20 USD upwards, or the equivalent in other currencies, from 2004 until now."
popsike only lists the ones that were sold for more than $20 on ebay, so that gives the false impression. Discogs is directed at a more specialist audience of collectors that may be willing to pay more for a record that they've been looking for for a while than the usual crowd as well.
The truth is that the vast majority of 78s that you can find are so common still that they are nearly worthless. If you can find anyone to take them off your hands, you can be grateful.
Here's what a well-known record auction site writes on its FAQ:
"unless you are a serious collector or have inherited an important collection, most of your records probably have little if any value. This is because the great majority of vintage records (like coins, stamps, postcards, comic books and other collectibles) are very common. Records were pressed by the bazillions, and there are many more records in existence than there are collectors seeking them."
Tim Gracyk has published an article that goes into more detail, if you need it.