Sorry I'm no help with the values Wadhams......I too would be interested in hearing thoughts on the values of these, especially the smaller Regular plate. I purchased one locally a while back in an antique mall, and although mine is a bit rougher, I thought I bought it cheap. They certainly do not come up for sale. In fact, I had no sale history knowledge when I bought mine, as I'd never seen any sell publicly, so I just bought it as I hadn't had any other opportunities to do so.
Always looking for Mobil items I don't already have!