Personal Trainer is very expensive to use, but getting scout players is more than enough for building teams that will win some trophies, There are a couple of posts of teams that have use personal trainer a lot to upgrade players to 8*/9* but if you ask me, doing such a thing at low levels is a waste and probably only recommended if your rich.
http://forum.topeleven.com/top-eleve...end-token.html
http://forum.topeleven.com/top-eleve...ream-team.html
For the record: It is currently cheaper to buy Football Manager 2013 than it is to buy 500 tokens so a lot of players will be "priced out" of using personal trainer. But we all love talented players!
Also scout players bought from the scout can sometimes develop into 7* by training.