One thing i will say though, even if he cant reach his full potential he should be fairly inexpensive to purchase, and then with training, when he gets better and you're in a better position, sell him and buy a better trainee and possibly buy another player as well. Until you get a few players that are dominant you should look to train and sell until you get awesome trainees, and can train them to be unbelievable players, that is my opinion.
Some people call this "day trading" and are against it, in my opinion it is the best way to accelerate your teams development.