Cheapest priced copy (Neon Dynasty Commander): $0.99 at Card Kingdom, near mint, their price list as of .
Spearbreaker Behemoth 
Creature — Beast · 5/5 · Rare · Neon Dynasty Commander · #132
Indestructible
{1}: Target creature with power 5 or greater gains indestructible until end of turn.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.99 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shards of Alara | 150 | Rare | $1.29 | $3.49 |
| Neon Dynasty Commander | 132 | Rare | $0.99 | — |
2 rulings from Wizards of the Coast
- 1 October 2008The ability checks the targeted creature's power twice: when the creature becomes the target, and when the ability resolves. Once the ability resolves, it will continue to apply to the affected creature no matter what its power may become later in the turn.
- 1 July 2013Lethal damage and effects that say “destroy” won't cause a creature with indestructible to be put into the graveyard. However, a creature with indestructible can be put into the graveyard for a number of reasons. The most likely reasons are if it's sacrificed, if it's legendary and another legendary creature with the same name is controlled by the same player, or if its toughness is 0 or less.