This really belongs in the rules section, not the PFS section. However, the special materials cost is applied to the base weapon, so it would be 3,300 gold.
EDIT: it really doesn't belong here as Drake pointed out, it's not a legal choice for PFS.
An example of this is if you calculate the cost of a Gargantuan Breastplate before modifying for Mithril you can then melt down the Mithril Breastplate and sell the Mithril for a profit.