You can't have 5 150k players and still have a decent bench. If you only train to gain money, 150k players are not the ones you would sell for profit. They should be sold way before that mark. You can't move a 150k player and make profit, his last season salary has been too high already. Even training him for your own team, I would stop trainin at 100k, perhaps get a new trainee and sometimes give him some training scraps.
Sure you can pay a little extra for those C spots, as their salary is a bit higher compared to other positions. I'd rather have 110k starters and 50k bench players, than 150k starters and 10k bench players.