Cheapest priced copy (Mirrodin): $0.35 at Card Kingdom, near mint, their price list as of .
Sphere of Purity 
Enchantment · Common · Mirrodin · #26
If an artifact would deal damage to you, prevent 1 of that damage.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mirrodin | 26 | Common | $0.35 | $0.49 |