well... considering the time is takes to make a steal would cost 2120 with mats lets call that 10600 for time alone. So yes 900 sounds like a lot if I need to find the mats think of it this way though.

Iron is 5g each and i need to get 300 so 1500 more gold.
Wood is 35g each and I need to get 200 so 7000 more gold.

As well as money lost by having characters seek out these specific items instead on the more valuable silver, gold, crude, alm, ect.

I think 45k from scratch I provide the mats sounds fair. However I can be reasoned with and can drop the price but from a monetary standpoint I would likely break even building 50 steel from scratch as I would continuing what my characters are doing... Just doesnt seem worth it to sell for much less.