Feign Death and Merchants
 

I believe you could do quest turn-ins and buy from merchants while using Feign Death. My memory is kinda fuzzy but I found this link.

I don't ever remember using FD to vendor but that sounds awesome. I always used sneak, but maybe they changed it before I started.

I used to do that on my necro for handing in quests. Was a neat trick.

Yep, I did it on quests. I dont know if it worked on merchants or not.

I didn't play a monk until Kunark, but from what I remember FD did not work for vendors during that time. It did work just fine for quest turnins.