Its not clear wed be that excited to draw a copy of the card naturally (though I may just be underrating it a bit when I say that), but when you just get given a copy of the card without having to draw it or even include it in your deck it suddenly becomes much more appealing
Thassas Oracle is generally seen as the more powerful one, and the other two are generally better suited to more casual levels
At the current box price, thats ~648,000 spent on average to pull one meaning the cards 448,000 market price actually represents a discount versus pulling it yourself
I know this seems limited to a Halfling deck or a deck where your commander is a Halfling, but there are a ton of ways for Equipment-heavy decks to discount the equip cost
Milling a card means putting the top card of your library into your graveyard if theres no card to put into the graveyard, no cards were milled
All is Dust is a solid $15+ despite existing as a GP Promo