Knowing which cards are valuable, in what grades, from which sets, requires serious study
Ive got just such a Zirda deck built, with a lot of delve into the dungeon cards, as WotCs Studio X made them a bit more expensive than they should have been because they werent entirely sure how theyd impact Standard
Surge foil borderless character cards appear only in Collector Boosters
Chances of Pulling : Dachsbun ex is easier to pull than some other heavy hitters but still not a guarantee
The original signature, an event card "Improvisation", also allows to immediately switch a role and then play something from that role with massive discount
Am I playing utility Creatures at 3 mana, like Thalia, Heretic Cathar