Looked at the cost of Truegold, mats vs finished product.
It's 950g for the mats (if bought on the AH), and they're selling at 2000-2200g, so over a 1,000g profit per transmute or 5,000g per day with five toons.
Interestingly enough, Pyrite is much cheaper to buy the finished bar than to buy the mats and transmute it myself.

Spend 28,800g buying the mats necessary to take the first five toons from 450 to 525 alchemy.
At current prices, that's under a week to repay the investment, which is pretty crazy.

So, five alchemists leveled up, some mats left over.