I think $400 to $425 would be more fair price selling to an individual person. If selling to a shop, or putting on consignment then $350 would not be out of the question. Though that would be more on the low end. If it is a shop remember they have to mark it up to make a profit from it.
Oh and as far as revolvers to semi goes. People that buy revolvers are the ones that are looking for revolvers.
Also most times around the holiday season people get a need for shopping money, and tend to sell cheaper to get the money they need.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.