They have a ton of free Jersey City post cards in the New Jersey room (I think that's on the second floor) of the Jersey City public library main branch. One has a picture of the Lincoln Park fountain and one has a picture of NJCU but there's a few others to choose from. Last I went a couple weeks back they were just out on a table with a note saying to help yourself

Kanibal may have cards, not postcards.

This is random but the UBS building in Weehawken has a gift shop in it. Only open during the week. The store is straight out of the 90s. I bet they have post cards still. They did like 3 years ago.

Edit: Best Wishes Card & Gifts

Give them a call in the morning and ask. Last time I was there they had really cool 80/90s postcards. Shocked they still had them on the rack.

They have a ton of free Jersey City post cards in the New Jersey room (I think that's on the second floor) of the Jersey City public library main branch. One has a picture of the Lincoln Park fountain and one has a picture of NJCU but there's a few others to choose from. Last I went a couple weeks back they were just out on a table with a note saying to help yourself

Total guess but maybe WORD would have one? Or possibly a hotel or restaurant (if it doesn’t have to be a tourism postcard). I can’t think of a restaurant off hand, but I’ve seen some places use post cards to give you your check.

I know you asked for JC, but the Hoboken Historical Museum is close and has lots of cool NJ oriented postcards in their gift shop.