Where do you farm elixirs?

The elixirs are extraordinarily stupid in this game. I'll never understand why they made the most important and commonly used item so crappy to come by. Even Bloodborne sells them. Where's the best place to get them? Do they ever sell them?

If Team Ninja is listening: Tune your game right and people will spawn with the correct amount of elixirs. This isn't the goddamn 90's. Friggin' amateur hour here...