The world has lost its collective mind over Captain Marvel. If you're looking to flip some of her keys for a profit, you'll need to get moving. Even a second printing of Avenging Spider-Man #9 is hitting $400.

Before Marvel dropped the first teaser for Captain Marvel, collectors were scouring eBay for high grade copies of Carol Danvers' first appearance in Marvel Super-Heroes #13. Just weeks ago, this was among the hottest comics on the market regardless of era. Now that we have our first official footage, that comic is poised to enter a new stratosphere, which I'll feature in a post this weekend. First, however, let me fill you in on an unassuming key that could be profitable for you: Avenging Spider-Man #9.

We've all gotten so used to calling Carol Danvers "Captain Marvel" that it's hard to believe that she was only given the upgraded title six years ago in the pages of AvSM #9. While it definitely had larger implications for female superheroes, it has become a highly collectible key, and the value is only going to keep rising as Captain Marvel takes on a bigger role in the MCU.

Marvel Studios officially announced the Captain Marvel solo movie in October 2014, so it's not surprising that by 2015 AvSM #9 was already experiencing its first boom, albeit a modest one with a high sale of a graded 9.8 at $225. As the excitement built, the following year saw that record sale jump to $400. In the past month, that figure has been nearly doubled; on August 29, a 9.8 AvSM #9 sold for an impressive $707. Keep in mind, that number was reached prior to the teaser trailer's drop. Wait until this time next month, and we'll likely see this coming in a near-mint-plus reaching the $800 range. We're already heading that way, it seems; two of the past three sales - all of which have been in the past week - have sold for just under $700.

Considering this comic is under 10 years old, finding copies in the upper grades is no rare feat. That explains why collectors are almost exclusively buying the 9.8s and the 9.6s. To put it in perspective for you, out of the 257 graded copies of AvSM #9 that have sold in the past 12 months, 206 of those were either 9.8 or 9.6. Speaking of that 9.6, you'd better act on that one quickly; its 90-day average is at $334 and rising, and the last sale was for $400 only days ago.

As Captain Marvel hysteria sweeps the comic market, all higher grades of AvSM #9 are climbing. Even an 8.5, which brought just $28 in 2016 has already sold for no less than $200 in three sales since May. For that matter, you can drop down to a 7.5, and you'll find that one sold for $143 last month.

Even the second prints are enjoying the rub from the movie buzz. A second-print 9.8 has skyrocketed to a new record-high sale of $400 within the past week. In July, two 9.6s sold for $119 and $113, respectively. Back in May, a second-print 9.4 brought $131.

And this is only the beginning. Grab up your copies now and hold onto them until 2019 when the movie gets closer to the premiere date.