Originally posted by Arachnyd:

I use silver arrows exclusively after Moder, so, if you didn't load up while you were looking for him, then yes, you'll need more.

Arach

What for? Silver arrows aren't any better than Obsidian for any living enemies and the only undead enemy you fight after Moder is Yagluth who is resistant to pierce so he shouldn't be fought with bows to begin with.
Also in the Plains you can just get Needle Arrows easily which is stronger.