According to Advertising Age magazine, the Fox talent-search show's Wednesday edition — when the voting results are announced each week — is more expensive than the Tuesday performances.
The Tuesday edition cost about $620,000.
It is the first time in memory that a show that does not air on Thursday night has topped the list of regularly scheduled shows, the magazine says.
Sunday night is the most-watched night of the week — but Thursday is in greater demand among advertisers like the movie studios and department stores that want to reach weekend shoppers.
"ER," "Survivor" and Donald Trump's "The Apprentice" (search) — all Thursday night shows — take up the next three places on the list.
"Some buyers were surprised 'The Apprentice' did not come in higher," the magazine wrote.
"A 30-second spot on average costs $409,877, according to Ad Age's survey of buyers, although NBC pegged the price closer to $500,000."
Among the other surprises on the list was a new show that is not even on the air yet, "The Contender," (search) a reality show about boxers.
The show, from "Survivor" producer Mark Burnett (search), was set to debut in November but now appears more likely to start in January.
"The Contender" — which will be hosted by Sylverster Stallone — is getting $300,000 per 30-second spot, a huge premium for a show that has not yet proven it can draw an audience.
Also, the magazine noted "Survivor" is getting richer. The price of an ad on the granddaddy of reality shows jumped from $390,000 last season to nearly $413,000 this year.