thanks!

seems particularly interesting that B, O, or Y economy would all have the same cash upgrade price to J.

i'd like to gamble on a basic economy upgrade DFW-ICN mid-week, although not getting it for a 15h flight would be more misery than i'd prefer. is mileage credit for J is not given to these but typically is for prior points + miles upgrades, think i'll see if i can find a seat i could upgrade immediately with that C space, which i'll proxy with a saver award search flight for dates.