I think the better option would be to make it the following:
When you try and list a player on the transfer list, at the moment it gets listed instantly, perhaps we can make so that when you try and list the player, it takes 1 hour before he is actually put on the market. During that 1 hour you have the option to change the price, or even cancel it all together.
This 1 hour window will allow mistakes in price to be fixed, and any last minute changes on mind regarding selling their player to be fixed. And this doesn't affect anyone else because no one will actually be able to see that the player has been set to list in 1 hour and so they won't know the price has changed or that the player is no longer going to be up for sale.