Cheapest priced copy (Mirrodin): $0.79 at Card Kingdom, near mint, their price list as of .
Slagwurm Armor 
Artifact — Equipment · Common · Mirrodin · #243
Equipped creature gets +0/+6.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
2 printings · $0.79 to $8.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mirrodin | 243 | Common | $0.79 | $8.99 |
| Salvat 2005 | L43 | Common | — | — |