There’s something more powerful than an Infinity Stone in our universe: An appearance in a Marvel movie.

In Captain Marvel, an old lunchbox featuring the likeness of Henry Winkler’s character “The Fonz” from the TV show Happy Days plays a small but crucial role in the film’s later scenes. Without spoiling anything too significant, Captain Marvel and her allies are on the hunt for a MacGuffin, and when they find it, they hide it in this Happy Days lunchbox.

The box is a real item sold in the 1970s. And ever since Captain Marvel opened in theaters last month, prices for that lunchbox have skyrocketed on eBay.

In the month or so before Captain Marvel opened in theaters, six of these Fonzie lunchboxes sold on eBay for an average price of $47.32. In the month since Captain Marvel debuted, ten lunchboxes have sold for an average price of a whopping $139.42.

In other words, the average price has basically tripled in the span of a few weeks — and the most expensive price paid before the movie opened ($71.60 including shipping) is now lower than the lowest price paid subsequent to Captain Marvel’s premiere ($75.20 for a very beat up lunchbox, plus shipping). The high price so far: $304 (shipping included) for a mint lunchbox that included the original thermos. That’s more than ten times what some lucky bidders were paying just weeks earlier.

eBay

If you are a lunchbox speculator with a collection you’ve got saved away for a rainy day, you may want to think about throwing your Fonz lunchbox up on eBay right now. There clearly hasn’t been this much interest in Happy Days memorabilia in quite a while. But beware: The boom may not last long. The collectibles company Entertainment Earth has announced they will be selling a replica of the Happy Days lunchbox from Captain Marvel this October for the relative bargain price of $14.99. If you just want a good lookalike for your Carol Danvers cosplay, that will probably be your best option.

If you are of the opinion that prices for the authentic Happy Days lunchbox have already jumped the shark, you can pre-order one of the replicas now.

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