Cheapest priced copy (Innistrad: Double Feature): $0.35 at Card Kingdom, near mint, their price list as of .
Bramble Armor 
Artifact — Equipment · Common · Innistrad: Crimson Vow · #188
When this Equipment enters, attach it to target creature you control.
Equipped creature gets +2/+1.
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
4 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Innistrad: Double Feature | 171 | Common | $0.35 | $0.49 |
| Innistrad: Double Feature | 455 | Common | $0.35 | $0.49 |
| Innistrad: Midnight Hunt | 171 | Common | $0.35 | $0.49 |
| Innistrad: Crimson Vow | 188 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 24 September 2021If the target creature becomes an illegal target, the Equipment remains on the battlefield unattached.
- 24 September 2021Attaching an Equipment with its enters-the-battlefield triggered ability isn't the same as using its equip ability. You don't pay mana for the attachment, and the timing restrictions for equip abilities don't apply.
- 19 November 2021Bramble Armor doesn't enter the battlefield attached to a creature. Instead, the Equipment enters the battlefield and then a triggered ability attaches it to a creature. You may cast Bramble Armor even if you don't control any creatures.