Is there a way to sell plot items in a saved game/character?

Reason I asked... just finished the Rogues of Quinn 1-3. Fun series,
nothing fancy. However, my character is a bit short of gold. (Played
4, written by a different person, it was... eh, OK but felt different,
not to mention it assumed you ended the module 3 with a "forgive and
forget" attitude - which I didn't)

I have a number of magic items apparently marked as plot, so they show
as zero gold pieces at the various merchants. I've got better items,
so I would like to sell these items for their true worth rather than
just drop them and I don't want to "cheat" extra gold... just what I've
rightfully stolen!