Cheapest priced copy (Adventures in the Forgotten Realms): $0.35 at Card Kingdom, near mint, their price list as of .
Dueling Rapier 
Artifact — Equipment · Common · Adventures in the Forgotten Realms · #140
Flash
When this Equipment enters, attach it to target creature you control.
Equipped creature gets +2/+0.
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Adventures in the Forgotten Realms | 140 | Common | $0.35 | $0.49 |