Thanks for the advice. I actually made it onto the first EWR flight of the day.
Newark is the most expensive airport I've been to. The trinkets were about 4x s more expensive than the lunch at Caliente's, and I only bought 5 small items...yikes! If you just want postcards, ask each vendor if the cards aren't visible. Don't believe any vendor that says EWR doesn't sell them. They are only trying to rip you off. The vendors that do carry postcards have slightly better prices on their stuff than those who don't sell them. It's an airport...what more can be said??

By the way, Caliente's Mexican restaurant has really good food, but stick to the appetizers. I had fajita nachos and tea. With tip, it was a little over $12 and there was plenty of food to satisfy a hungry traveller.