Cheapest priced copy (Foundations Commander): $1.49 at Card Kingdom, near mint, their price list as of .
Master Transmuter 
Artifact Creature — Human Artificer · 1/2 · Rare · The Brothers' War Commander · #87
{U}, {T}, Return an artifact you control to its owner's hand: You may put an artifact card from your hand onto the battlefield.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
6 printings · $1.49 to $29.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters | 58 | Rare | $3.99 | $15.99 |
| Archenemy | 7 | Rare | $5.49 | — |
| The Brothers' War Commander | 87 | Rare | $3.99 | — |
| Conflux | 31 | Rare | $4.99 | $29.99 |
| Foundations Commander | 67 | Rare | $1.49 | — |
| The List | CON-31 | Rare | $3.99 | — |
2 rulings from Wizards of the Coast
- 7 August 2020Master Transmuter can be returned to its owner's hand to pay the cost of its activated ability.
- 7 August 2020The artifact card you put onto the battlefield when the ability resolves may be the same card that you returned to your hand when you paid the cost. If so, it returns to the battlefield as a new object with no relation to its previous existence.