Cheapest priced copy (Amonkhet): $0.49 at Card Kingdom, near mint, their price list as of .
Cartouche of Solidarity 
Enchantment — Aura Cartouche · Common · Amonkhet · #7
Enchant creature you control
When this Aura enters, create a 1/1 white Warrior creature token with vigilance.
Enchanted creature gets +1/+1 and has first strike. (It deals combat damage before creatures without first strike.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.49 to $6.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Amonkhet | 7 | Common | $0.49 | $6.99 |
| Foundations Jumpstart | 178 | Common | $0.69 | — |
| The List | AKH-7 | Common | $0.79Out of stock | — |
3 rulings from Wizards of the Coast
- 18 April 2017If the target creature becomes an illegal target before a Cartouche spell resolves, the spell doesn't resolve. It doesn't enter the battlefield.
- 18 April 2017Cartouche is an enchantment subtype with no special meaning. Other cards may care about which enchantments are Cartouches.
- 18 April 2017Each Cartouche is an Aura with "Enchant creature you control." If another player gains control of either the Cartouche or the enchanted creature (but not both), then the Cartouche will be enchanting an illegal permanent and be put into its owner's graveyard as a state-based action.