Cheapest priced copy (Ravnica: City of Guilds): $0.35 at Card Kingdom, near mint, their price list as of .
Dryad's Caress 
Instant · Common · Ravnica: City of Guilds · #160
You gain 1 life for each creature on the battlefield. If {W} was spent to cast this spell, untap all creatures you control.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica: City of Guilds | 160 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 1 October 2005The spell checks on resolution to see if any mana of the stated color was spent to pay its cost. It doesn’t matter how much mana of that color was spent.
- 1 October 2005If the spell is copied (such as with Twincast), the copy will never have had mana of the stated color paid for it, no matter what colors were spent on the original spell.