Sigarda, Heron's Grace is the weakest option of the three on pure power level, but its an annoying threat and I like the idea of having a flying, go-wide threat to complement the go-tall game plan in the rest of the deck
On TCGPlayer, lightly played copies go for a market price of around $100, with near mint cards coming in around $120
Shattering Spree Sometimes, you gotta pack a Shattering Spree, as inefficient as it seems
Set: Shining Victories Printing: Unlimited Increase: +$12.02 Current Market Price: $21.65 Blue-Eyes Spirit Dragon has been reprinted numerous times, including most recently in the Blue-Eyes White Destiny Structure Deck that released in February, so players have many more affordable options than this, the cards original printing
Self-mill, discarding, and sacrificing your own permanents will fill your graveyard all the same, and delirium doesnt really care why or how youre getting the cards in there