Cheapest priced copy (Theros): $0.35 at Card Kingdom, near mint, their price list as of .
Viper's Kiss 
Enchantment — Aura · Common · Theros · #109
Enchant creature
Enchanted creature gets -1/-1, and its activated abilities can't be activated.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Theros | 109 | Common | $0.35 | $0.49 |