I think it's the old "nice to have vs need to have". Anyone who actually needs a part for their build has no problem paying a fair and reasonable price for something. I have found that lowballing comes when people want to "add" to their collection. I know when I sell household stuff locally, I normally put a small price on it to keep the hoarders away. More often than not, I end up giving it to the person for free when they show up.
