Cheapest priced copy (Modern Horizons 2): $0.35 at Card Kingdom, near mint, their price list as of .
Wavesifter 
Creature — Elemental · 3/2 · Common · Modern Horizons 2 · #217
Flying
When this creature enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Evoke {G}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 2 | 217 | Common | $0.35 | $0.49 |
| Murders at Karlov Manor Commander | 220 | Common | $0.35 | — |
3 rulings from Wizards of the Coast
- 18 June 2021The tokens are normal artifacts. For example, one can be sacrificed to activate the ability of Breya's Apprentice and one can be the target of Break Ties.
- 18 June 2021The token is named Clue Token and has the artifact subtype Clue. Clue isn't a creature type.
- 18 June 2021You can't sacrifice a Clue to activate its own ability and also to activate another ability that requires sacrificing a Clue (or any artifact) as a cost, such as that of Lonis, Cryptozoologist.