Cheapest priced copy (Throne of Eldraine): $0.35 at Card Kingdom, near mint, their price list as of .
Rosethorn Halberd 
Artifact — Equipment · Common · Throne of Eldraine · #175
When this Equipment enters, attach it to target non-Human creature you control.
Equipped creature gets +2/+1.
Equip {5} ({5}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Throne of Eldraine | 175 | Common | $0.35 | $0.49 |
| Jumpstart 2022 | 722 | Common | $0.35 | — |
| The List | ELD-175 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 4 October 2019If there are no creatures to attach Rosethorn Halberd to when it enters the battlefield, it simply remains unattached.