I've never seen any gift boxes sold for that high. Level Up Gift Boxes are 35-40m. Level 40 ones are 12-15m; level 100/180B are 10-15m, and level 140 ones are 30m, give or take. The prices have been inflated a lot, but that's still nowhere near the exaggerated three digit figures you threw out here, so if anyone is buying them for that high, they're idiots in the first place.
Which is why I said PER DAY.
Just going to drop this... no one seems to care.
Trials are terrible, and should get replaced by a better (but similar) system built more for parties and rewarding more for parties. Right now they're just a stalling nuisance with typo-ridden dialogue that is built to solo - something rarely seen in an MMO. But I guess since one player in Trickster can dish out in one or two hits the same damage multiple parties do in other games during an entire boss fight, partying seems rather pointless.