For me it is not too slow or too popular. The problem lies more on the majority of the trainers itself.
1. A lot of them/us, do not know or take to consideration the small difference of the increase in pops in each level of trainer. Maybe some of them are not that informed about this so they just bid and bid and bid until they get the trainer that they want believing that the market's value is in par to the effect of the trainer.
2. A lot of them are still not well verse about the importance of secondaries so a lot of players that are being trained right now are still those one/two tricks ponies. And LI is still very popular right now that I believe a lot of the guards that are being trained as well as the bigmens are LI players.
3. Lastly, we do not have a lot of GM that trains actually. Because if we have, the market price should have been lower because Supplies will be higher than the Demands.
With this, I believe that RIGHT training is profitable. And if we reverse those issues that I pointed out, the market should become a more efficient and cheaper one.