Be prepared to pay the price for a proper Starlord costume this Halloween—his most vital retro prop is hot on eBay.

A 1979 Sony TPS-L2 Walkman cassette player recently sold for $613 on virtual auction site, and many more are currently listed. Another sold prior to that for $820 on eBay. Other bidders obtained less mint versions of the cassette player for $80 to  $300.

The iconic Walkman is featured in the Marvel Studios box office hit “Guardians of the Galaxy” as the prized childhood possession of the protagonist Peter Quill, aka Starlord.  He listens to his homemade mix tape throughout the movie, Awesome Mix Vol. 1, which provides the soundtrack of 70s pop hits. The film’s soundtrack is currently on the verge of topping the Billboard chart for album sales. awesomemix

Cassette tapes have been long relegated to the bargain racks at thrift stores since the advent of the compact disc. Leave it to Starlord to lead the revival of this dead music format. Much like the rise of vinyl over the last decade, the nostalgia created by the film could make the cassette tape once  again a popular format for new releases by your favorite bands.

Sadly in the meantime, you can only buy the Guardians soundtrack on CD or digital .mp3.   Or you can keep it retro and dub your own, if you can afford a cassette player that is. Collectors take note that director James Gunn tweeted on August 1 that he is infact working to releasing the soundtrack on cassette.

The surge in popularity of the Walkman is also of huge value to Sony itself. According to Front Row Analytics, a firm that analyzes such things, the Japanese tech company received $770,386 in “product placement value” during opening weekend of the film when it grossed more than $94 million.