Peterborough & Norwich would be two good examples who develop players and sell them on for big profits
Peterborough are a bit different as they tend to search non league more often than not for players and are willing to pay a decent fee in the hope of them developing them into good players and selling for a good profit, they have done this many times over the years and is a good model.
We rely upon picking up freebies and hoping they improve.
We used to be willing to pay up front fees but normally to higher league clubs youngsters, even under Power, but that seems to have stopped in the last couple of years. Gladwin and Luongo were cases in point, but for every Luongo you get several like Rodgers, BOO, Goddard, Murray, Starkey, Hylton, Norris etc etc several of those we actually spent money on.
Crewe are a great example of bring youngsters through from youth teams and selling on for large fees, as we have gone through many times in the past on the TEF.
There are way more clubs that want to be like that than actually achieve it though.
With the TV money not filtering down much to the lower leagues it will be the only way some clubs will survive, selling on to Championship clubs, very rarely will a club down here sell to a Premier League team, unless they are recently promoted there.