Sure, you've been able to buy cheap plastic arc reactors for a while, but this is the real-deal Mark I "Hero" reactor from the actual movie. And it's just one of a boatload of props and costumes up for auction.
It's all part of the official Iron Man prop and costume auction being put on my Propworx. You'll be able to snag stuff like suits worn by Tony Stark, the Sonic Taser used by Obadiah Stone to paralyze Stark (complete with earplugs) or even the Stark Industries wet bar Tony brought with him into the desert.
The auction itself is taking place during C2E2, the Chicago Comic and Entertainment Expo, next month from the 16-18 of April. If you're in Chi-town, head on over to McCormick Place on those dates to check the goods out in person and make bids. If you're far away, you can bid online at the auction site. [Propwerx]