Cheapest priced copy (The Brothers' War Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Workshop Elders 
Creature — Human Artificer · 4/4 · Rare · The Brothers' War Commander · #102
Artifact creatures you control have flying.
At the beginning of combat on your turn, you may have target noncreature artifact you control become a 0/0 artifact creature. If you do, put four +1/+1 counters on it.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Brothers' War Commander | 102 | Rare | $0.49 | — |
| Throne of Eldraine | 318 | Rare | $0.49 | — |
| March of the Machine Commander | 245 | Rare | $0.49 | — |
3 rulings from Wizards of the Coast
- 4 October 2019If another effect later causes the artifact to become a creature and sets its power and toughness as it does so, that creature will have that base power and toughness; it won't be 0/0. Notably, crewing a Vehicle does not set its power and toughness, so a Vehicle's base power and toughness remain 0/0 if you crew it.
- 4 October 2019The effect of Workshop Elders's triggered ability lasts indefinitely. It doesn't wear off during the cleanup step.
- 4 October 2019An artifact that becomes a creature due to Workshop Elders can't attack unless you've controlled it continuously since your turn began.