Cheapest priced copy (Fate Reforged): $0.35 at Card Kingdom, near mint, their price list as of .
Abzan Advantage 
Instant · Common · Fate Reforged · #2
Target player sacrifices an enchantment of their choice. Bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fate Reforged | 2 | Common | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 24 November 2014You determine which creature to put counters on as the spell or ability that instructs you to bolster resolves.
- 24 November 2014You can target any player with Abzan Advantage, even if that player doesn't control an enchantment.
- 24 November 2014The enchantment will have already left the battlefield when you bolster 1.
- 24 November 2014Bolster itself doesn't target any creature, though some spells and abilities that bolster may have other effects that target creatures. For example, you could put counters on a creature with protection from white with Abzan Skycaptain's bolster ability.