If youth academy and Mr. Scout don't work for you, and you cannot find when they release the generated players (trust me they exist but there's probably a lot of demand, since it's not just you looking, especially beginning of season), there's not much else to do other than tank a season (or 2) to drop down from the top, so then there would be teams above you selling. You can also try negotiations if you have a lot of patience (I don't.)