Absolute lowest item costs?

[MaxWilson]

I can confirm that sites with a construction bonus (Steel Ovens) definitely affect forging costs, and I'm 80% certain it's an additive and not multiplicative bonus. So a Steel Oven (20% bonus) and a Dwarven Hammer give you items for 55% of normal cost, rounded down. 5 gem items cost 2, and 10 gem items cost 5. Adding FotA would take this down to 1 and 2 respectively.

-Max