IMO, you can get abetter "feel" for what the going market value of a particular item might be by searching Gun Broker and the other firearms auction sites. The main thing to look for is what examples in similar condition have actually sold for, not what's being asked.
If an item similar to yours isn't drawing any bids at the starting price, it's a pretty good indication that either interest in it is limited and/or it's been set at or above the top-dollar figure for most folks.
Collectors prize original condition above all else. When we're talking a fairly common antique model in an obsolete caliber it almost has to be pristine get their attention or their bids.
