I found a nice PLUMB 3.2 double bit today at a local antique shop (head only) and started looking for a value but can't seem to find anything definitive like a "Gun Blue Book" online. Is there a source for such valuation? Looking at ebay, the price is all over the board. They wanted $20.00 for it but seemed a little high to me. I'd like to restore one for a camp axe so the double bit really isn't the one for me, but it got me thinking about how to know a deal when I see on in the future. Got any sources for valuation?