hurasser

The MTK guide says that coal costs 91.6 gp/coal. 10 workers produce 50,000 gp worth of coal per day (assuming at least 750,000 gp in vault and 100% approval). 50,000 gp / 91.6 (gp/coal) = 545.85 coal So that would give you abuot 545 coal each day.

I think you can buy them from the slayer masters. Don't know the price.