Cheapest priced copy (Commander Legends): $0.35 at Card Kingdom, near mint, their price list as of .
Sifter Wurm 
Creature — Wurm · 7/7 · Uncommon · Commander Legends · #254
Trample
When this creature enters, scry 3, then reveal the top card of your library. You gain life equal to that card's mana value.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 254 | Uncommon | $0.35 | $0.49 |
| Hour of Devastation | 135 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 10 November 2020For cards in your library with {X} in their mana costs, X is considered to be 0.
- 10 November 2020Once Sifter Wurm's triggered ability begins to resolve, no player may take other actions until it's done. Notably, opponents can't try to change your library after you scry but before you reveal the top card of your library.