MITH - 16k bars needed.
Total cost of 1k bars = 845k
Total price of 15k arrowtips = 840k
Loss from 1k bars = 5k
Total loss = 80k
Can do 10 per minute, therefore 600 an hour at Neitiznot.
Smelting = 18kxp per hour.
Smithing = 50kxp per hour.
I will lose approx 80k from 70-80 smithing, but because of price changes, probably a bit more.