I'm of the opinion that you shouldn't trust black market prices to be "base" prices because a) much rarer for the frags you want to show up, and b) limited number of frags to buy at one go (compared to treasure of the sage). As such it makes sense that this would be compensated somewhat by "discounted prices".

Obviously this is speculation and unconfirmed, but my point is still don't rely on black market to be a good comparison point.

it's called a "black" market for a reason ^^, you can get deals as well as get ripped off your goods...

Black market prices are copy paste from cn, since hokage minato was considered a real rare back in a day his frag price in black market was 1000cp/frag. EN servers had him given away left and right as jackpots (infamous minato shisui meta), then redeemables and his price nowadays oscilates around 120-150cp/frag. Either way I wouldnt use black market as a price reference, since we often had answers from mods that ninja in X event is better/worse deal than in Y to make more variety, while in reality most of those prices are what they are and they have hardly any reflection in what ninja is worth in actual game.

You could think mei would be that expensive for an outdated ninja because of milking proces for skillbooks, but up until now she was virtually unobtainable through events (she might have appeared in 1ingot sales, cant say because i literally never look there). Perhaps somebody didnt plan that right. Would she be usable again with all necessary books (mystery, passive, chase)? Yes. Would she become sudden op? No. Gotta keep waiting for skill experiments to finally be implemented.

That is 240 coupons for 3 fragments.. so thats 80 each.. so almost as good a deal as treasure of sage.

Mei have been available in a lot of bad events like tailed beast, fishing mania and those special events that appear only for the holidays.

That said what garv points out is the fact the supposed to be basic price in treasure of the sage is actually 20% higher than the real basic price black market shows.

So when you get a 30% discount in that event is not actually a real 30% discount but only a 10%.

I sincerely doubt he cared about her availability considering his bp and the fact the picture itself shows he owns 80 frags of her.

I am, on the other hand, quite sure he cares about not being fooled by oasis.

That said, at this point of the game, makes no sense 80 of her frags costs more than 3/4k coupons.

Why? Because even once you fully skillbroken her you just got a slightly better version than edo roshi that costs 12k coupons, so her full set of breakthroughs cannot cost as much as getting naruto six paths + edo minato.