Cheapest priced copy (Avatar: The Last Airbender): $0.35 at Card Kingdom, near mint, their price list as of .
War Balloon 
Artifact — Vehicle · 4/3 · Uncommon · Avatar: The Last Airbender · #159
Flying
{1}: Put a fire counter on this Vehicle.
As long as this Vehicle has three or more fire counters on it, it's an artifact creature.
Crew 3 (Tap any number of creatures you control with total power 3 or more: This Vehicle becomes an artifact creature until end of turn.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Avatar: The Last Airbender | 159 | Uncommon | $0.35 | $0.49 |