Correct me if I'm wrong, but is this the guy in Waukeen's Promenade just East of the Adventurer's Mart? If so, he has disappeared on me and I'm not sure if this is normal or not. At any rate, I've just emerged from Watcher's Keep and sure could use his services.
If this isn't the guy, who the heck is he?

You won't meet Cespenar 'til Throne of Bhaal. Save your Watcher's Keep loot in your bag of holding for your post-Irenicus days.

By the way, once you meet Cespenar, you won't forget him. He's an excellent character!

Sweet. I was worried for a while.

BTW, what might have happened to that fat merchant next to the AM? I have a horn of blasting that needs improvement.

You can also find him sometimes in one of the nearby stores.
Enter thru one of the doors above Adventurer's Mart. When you see a store filled with fruits you got your man.