Cheapest priced copy (Modern Horizons 2): $0.35 at Card Kingdom, near mint, their price list as of .
Etherium Spinner 
Artifact Creature — Human Wizard · 2/1 · Common · Modern Horizons 2 · #40
Whenever you cast a spell with mana value 4 or greater, create a 1/1 colorless Thopter artifact creature token with flying.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 2 | 40 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 18 June 2021If a spell on the stack has {X} in its mana cost, X is the value chosen for it when determining that spell's mana value.