Yay, you just showed us that SGs don't add salary with HA/DR/PA, but you do need some potential for those skills. I never intended to imply that secondaries have a zero cost in terms of potential cap. We wouldn't have needed Josef Ka to figure out the potential cap if the answer had all been salary. Duh. But that fact doesn't mean you can't add an acceptable level of secondary skills to a lower potential guy, which is what I took your point to be.
And as far as the overall TL economy goes, yeah I think prices have definitely fallen, and then flattened, for high salary players, it has stabilized for lower salary players. This is especially true for those salary segments that no longer get put on the TL automatically after their owners go bot. So players in the 10-25K salary range have a reduced supply, and their price reflects that. As you go higher on the TL there can be a bit more supply, so prices moderate. At very high salaries, prices are also flat, as potential buyers are reduced due to fewer teams being able to support those salaries. I picture a graph of TL price versus salary are exponential, rising relatively fast a low salary, and then flattening off.
Then, let's say you are going to train your guy for 2 extra seasons over what a star potential player would need to cap. And let's assume that we take two players, one star, and one p-allstar, superstar, whatever. They're trained exactly the same for three years, but you're going to train 2 more seasons before selling. The star guy gets sold after his third. How much salary are you paying in that 4th and 5th seasons? if we just say 30K in the 4th season, and 50K in teh 5th, that's a lot of money over 14 week season. If instead the star guy trainer recycled to a new star trainee, they're only paying ~5K for the trainee salary. In that case, you sure better be getting at least 600K net on sale price-purchase price.
So I'll reiterate: you can make better palyers with higher potential, you can sell them for a final price that's higher, and they'll be more useful to your own team. But I do not agree that you won't make money training and selling a lower potential player with a good build.