Denny,
$50 will probably be pretty close for the paint. Add about another $30 for hardener and $15 for reducer. That # is Single Stage Urethane. Could get their Omni MAE acrylic enamel a lot cheaper.
You probably wouldn't paint your mailbox with the old enamel the factory used then. That and the fact that the cleaning and prep done at the time wasn't all that great meant the old paint didn't last long, just long enough to get it to the customer.
Bob
p.s. No, I worked at Joliet. Put 13 years in before I tired of getting laid off all the time. My Dad put in 35 and most of his friends worked there so I kind of grew up with the place. They all had "yellow blood".