I agree with bballchamp, that he doesn't need a high level trainer. I'm using a level 3 trainer, I'm training two allstars who had mediocre starting skills. I'm few seasons away from making them highly efficient 30k SFs. My third trainee was MVP, but I'll keep him with the other two at about 30k salary.
If I was starting in a low div, I would look for trainees with as high starting skills as possible, no matter the potential, and train them with a cheap level 2 or 3 coach. The can be good starters in lower leagues, and even backups in highest leagues, especially with the upcoming blank lineup removal.
For my main trainee I aim at something like
12/10
12/12
12/9
12/10
9/9
Extremely salary efficient, and cheap to train. Maybe I wouldn't mind a star or even starter potential(lower leagues), they would be very fast to finish training.