you can simple get it on a Monday, why would you want to buy it?
That can only be done by the ones that followed the information on the outside websites, AFTER the quest was discovered.
For the ones that made the option before the hernando quest was discovered... they cannot get the 3 piece of the note. Same thing with the 2 key.
Those are options. For the ones that started playing 24 months ago or after, those things where already knew and it is just following the tutorials.
For the other ones... they could not get those 2 special items.
With the shop, those things got into a lucky drop on the bags or chests. Even with a less than 1% luck, a few of those are appearing and can get into people that already made the hernando quest. So the 3 part is not usable by them.
That´s why it, finally, got into the market option.