There are thousands of itemes in this hobby, many of which turn up each day. None of us is knowledgable enough to know what they are worth. As most of us do, we accumulate these items, go to a petroleum show, rent one or more spaces, rent a room if it is more than a one day meet, put our items on the table and see what we can get for them. Or we put these things on ebay, pay them a commission and list the items at what we would like to get for them. This is how we determine what things are worth.
Author, 1st & 2nd editions of Gas Pump ID book, 3rd edition is now available at
www.gaspumpbible.comAir Meter ID book also available