Cheapest priced copy (Scars of Mirrodin): $0.35 at Card Kingdom, near mint, their price list as of .
Vault Skyward 
Instant · Common · Scars of Mirrodin · #51
Target creature gains flying until end of turn. Untap it.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Scars of Mirrodin | 51 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 1 January 2011Vault Skyward can target any creature, including one that already has flying or is already untapped.
- 1 January 2011For flying to work as an evasion ability, Vault Skyward must be cast before the declare blockers step begins. Once a creature has become blocked, giving it flying won’t change that.