I sold one recently on THAT site for a Tenner. It's about what they are worth these days.
I have had a few of the plastic variants in the past also.
They were manufactured by MANROY because you couldnt get the metal ones anymore in quantity.
An enquirey to metal box Company yielded a Yes to manufacturing more. BUT, they wouldnt entertain an order for less than 25,000 Minimum! It wasnt worth them tooling up & running a production run for less than that amount!