Cheapest priced copy (Scars of Mirrodin): $0.35 at Card Kingdom, near mint, their price list as of .
Flight Spellbomb 
Artifact · Common · Scars of Mirrodin · #155
{T}, Sacrifice this artifact: Target creature gains flying until end of turn.
When this artifact is put into a graveyard from the battlefield, you may pay {U}. If you do, draw a card.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Scars of Mirrodin | 155 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 1 January 2011For flying to work as an evasion ability, an attacking creature must be granted flying before the declare blockers step begins. Once an attacking creature has become blocked, giving it flying won’t change that.