Buying young/youth players from top end Championship or Premier League clubs is probably one of the few ways to get proper bargains now. They're all loaded and their academies churn out so many youngsters that they're more likely to be willing to let those players who they don't think will make it go fairly cheap.
Just thinking about it, that strategy has worked fairly well for us in recent years. Off the top of my head, Roofe, Brannagan, Ledson, Lundstram, McGuane, Henry, Moore we all got from Premier League youth teams or higher end Championship clubs for free/quite cheap. (feel free to correct me if I got any of those wrong or missed some lol).