When i was in the first levels I didn't want to waste tokens for them. Now, I check the market and when I find one that I like, I spend a token or two to buy him. Of course I choose the attractive ones ( not older than 24-25y, with an SA maybe, double position etc ) I usually sell them immediately or I train them a bit to raise their price. I don't even care if it is the end of the season because if they stay for the next season I only have less profit, i don't lose money.