Looking at Special Materials, it seems Adamantine lists it's modifiers as costs instead of prices unlike some other materials.
If this is the case, does that mean that, with +3,000gp cost, an adamantine weapon has a price of +9,000gp?
Looking at Special Materials, it seems Adamantine lists it's modifiers as costs instead of prices unlike some other materials.
I'm pretty confident that "cost" should be read as "price" in this one and only case, because Ultimate Equipment's listing does say "price." They should probably errata that in the CRB, because your confusion was perfectly reasonable.
The adamantine dagger is listed as 3,002gp; the battleaxe, 3,010gp. There's no reason for these to get over 60% off compared to, say, an adamantine warhammer or earthbreaker or scythe.