Think you've pretty much hit it on the head there! :argh:
Try reading a copy of Plant and Farm trader,you'd love it, barely a price published in there, nearly everything POA! It's like their own secret world.
I'm different than you I would rarely if ever phone up and request a P.O.A. My opinion is if it's a good price the vendor would be please to state it not hide it.
You obviously are not as put off as you suggest, as you seem to have enquired at Boys' about the Autocar.