Cheapest priced copy (Duel Decks: Elves vs. Inventors): $23.99 at Card Kingdom, foil, near mint, their price list as of .
Goblin Welder 
Creature — Goblin Artificer · 1/1 · Rare · Urza's Legacy · #80
{T}: Choose target artifact a player controls and target artifact card in that player's graveyard. If both targets are still legal as this ability resolves, that player simultaneously sacrifices the artifact and returns the artifact card to the battlefield.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
6 printings · $23.99 to $1099.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2014 | 177 | Rare | $24.99 | — |
| Commander Anthology Volume II | 101 | Rare | $27.99 | — |
| Duel Decks: Elves vs. Inventors | 35 | Mythic | — | $23.99 |
| Judge Gift Cards 2011 | 8 | Rare | — | $179.99 |
| Secret Lair Drop | 1617 | Rare | $23.99 | $32.99 |
| Urza's Legacy | 80 | Rare | $47.99 | $1099.99 |
One ruling from Wizards of the Coast
- 1 August 2008As the new wording makes clear, both targets must still be legal as the ability resolves in order for it to do anything. If either one or both has become illegal, nothing gets sacrificed and nothing gets returned to the battlefield.