I think a price fishing forum would be a waste of time. It's actually the lazy way to have somebody else do the research for you. Go to Ebay completed listing for comparables, and that will cover nearly everything.
If you want to sell the item, then list it and see where it goes. If you have no idea what something is worth, chances are you have little invested in it and anything over that is profit. Some folks seem obsessed to get every last possible cent out of something they sell.
Most people with websites clearly state they don't do appraisals. I do on my website, and I still get requests for "what's this worth ?".