IIRC for a Gargantuan dragon you get enough armor for either two or four sets of medium plate & large shields. And I thought for mundane gear that the materials cost was 1/2 final value. Which means that the armor-quality portions of dragon hide is worth 3,000-6,000gp. (possibly more if the 3400gp price for dragonhide plate does not include the shield)
The rest of the dragon hide is more than likely valuable but not armor worthy. I imagine there's a pretty rich market for dragon hide to make items of elemental resistance, cloaks of protection, and magic boots & belts. Not to mention mundane items of clothing. Think of the spoiled noble with his dragon scale boots.
Dragon fangs probably make decent foundations for magic weapons ranging from arrows to swords.
So a dragon's corpse is probably a fairly sizeable treasure on its own.
