Sorry about the confusion, but the one with 3 Bosscoins is a visual glitch. 80% of 191 is 38.2, which gets rounded up to 39 Bosscoins. Is this from the iOS or the Android OSM app?
The more expensive players are more difficult to sell. And then there is the randomnes that could either be in your favor or not. Sometimes you sell a couple of players really quickly and other times you will have to wait days before they get sold.