I know is post is quite old, but adding this comment so if someone is googling for a fix like me, it could help. I just possibly solved this same issue I was having I came across some posts talking about manually adjusting and then adjusting back your speechcraft skill. Well that did nothing. I found another that mentioned speechcraftmod So in console player.getavinfo speechcraftmod This was showing a -200 value...so I figured I'd just change it and see what happens. player.modav speechcraftmod 200 This sets it to 0. I went up to vendor...sell items now have positive values! I then buy a breastplate from the vendor, turn around and try to sell it back and the sell price is around 1/4 or so (I'm not mathing =P). The same posting (by whismerhill) I saw said a -100 value in the speechcraftmod setting will make vendors sell items for 0 gold. Not sure what changed it, but I'm now happy I have a possible fix. Now to just play the game and see.