I’m thinking about selling once fired brass but don’t know how much people are willing to pay. I don’t want to be like “that guy” who sells a wasr10 for a thousand bucks. 
I was thinking maybe about 15 cents a casing?
15 is a bit high in my area.
I did some cursory looking on some of the online places I use, average is around 6 to 8 cents a case, with the 6 cents running if you buy 1000, add in shipping on top of that though.
Last I bought was mixed head stamps (unprocessed) at a gunshow, my guy had buckets full and it was going for $5/100 out the door. That was about 3 months ago.