Is there some sort of skill I've missed to get source? Is it possible to "harvest" source?

I'm at the end of the reaper's coast area. I've multiple source point slots on my charaters and a ton of skills which require source. But I still don't know how to get source. Okay, there're this occasional source puddles but that's about it. I used up the purge charges. On top of that I get robbed of the few source points I saved by quests (e.g. Love Has a Price).