Cheapest priced copy (Modern Horizons): $10.99 at Card Kingdom, near mint, their price list as of .
Goblin Engineer 
Creature — Goblin Artificer · 1/2 · Rare · Modern Horizons 1 Timeshifts · #16
When this creature enters, you may search your library for an artifact card, put it into your graveyard, then shuffle.
{R}, {T}, Sacrifice an artifact: Return target artifact card with mana value 3 or less from your graveyard to the battlefield.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
5 printings · $10.99 to $54.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 1 Timeshifts | 16 | Rare | — | $18.99 |
| Modern Horizons | 128 | Rare | $10.99 | $16.99 |
| The List | MH1-128 | Rare | $10.99 | — |
| Secret Lair Drop | 2103 | Rare | $15.99 | $16.99 |
| Time Spiral Remastered | 345 | Special | $11.99 | $54.99 |
2 rulings from Wizards of the Coast
- 19 March 2021Because targets are chosen for activated abilities before costs (such as "Sacrifice an artifact") are paid, Goblin Engineer's second ability can't target the artifact that will be sacrificed to pay its cost.
- 19 March 2021If a card in a player's graveyard has {X} in its mana cost, X is considered to be 0.