score:6
There's no other way but to go on the carrier's website and check. It'll likely be split into categories of something like "domestic" "international". Also, frequent flier statuses will drastically wary this price to the extent of the very information not being available to people below certain status. (You bet that guy who flies 500 000 miles every year with the airline ain't going to pay 9 dollars an hour for wifi! Quod licet Iovi, non licet bovi.)