Halfway through the 10-day eBay auction, bidding for the finest known copy of Action Comics #1 has surpassed $1.95 million.

Owned by Darren Adams of Pristine Comics in Federal Way, Washington, it's just one of two copies of Superman's first appearance to receive a 9.0 rating from the Certified Guaranty Company. The other, previously owned by actor Nicolas Cage, sold at auction in 2011 for a record $2.16 million. The difference between the two is that the Cage issue had "cream to off-white pages," while Adams' copy is considered to be in pristine condition.

Bidding has slowed considerably as the price inches higher: The comic jumped from a starting price of 99 cents to more than $1.6 million in the auction's first day. Still, already this morning the price has moved from $1.8 million to a little more than $1.95 million. It appears just nine people have participated in the auction, for a total of 27 bids.

The auction continues through Aug. 24, with a portion of the proceeds going to benefit the Christopher & Dana Reeve Foundation, dedicated to curing spinal cord injury. Adams, who acquired the comic several years ago, is only its fourth owner. He said he recently turned down an offer of $3 million, deciding instead to sell the book on eBay.

Only about 30 unrestored copies of Action Comics #1 are thought to exist.