I've only done one playthrough so I may have missed some, but I think the druid grove is still your best bet. I know of two in the goblin camp, and 2 in the underdark, as well as one in the Zhentarim Hideout, but none could be called "reliable".
I guess I need to stop eradicating the Druids for the time being then. Or I could just push on to the Goblin camp.
Was just wondering if there was some wayward traders hanging about that I haven't stumbled into yet.