Cheapest priced copy (Marvel Super Heroes Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Infinity Formula 
Artifact — Equipment · Common · Marvel Super Heroes Commander · #601
When this Equipment enters, attach it to target creature you control.
Equipped creature gets +1/+2 and has "Whenever this creature attacks, you gain 2 life."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Marvel Super Heroes Commander | 601 | Common | $0.35 | $0.49 |