Cheapest priced copy (Dominaria): $0.35 at Card Kingdom, near mint, their price list as of .
Arbor Armament 
Instant · Common · Foundations Jumpstart · #628
Put a +1/+1 counter on target creature. That creature gains reach until end of turn. (It can block creatures with flying.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
4 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria | 155 | Common | $0.35 | $0.49 |
| Foundations Jumpstart | 628 | Common | $0.35 | — |
| Jumpstart | 376 | Common | $0.35 | — |
| The List | DOM-155 | Common | $0.35 | — |