Cheapest priced copy (Jumpstart): $0.49 at Card Kingdom, near mint, their price list as of .
High Sentinels of Arashin 
Creature — Bird Soldier · 3/4 · Rare · Khans of Tarkir · #13
Flying
This creature gets +1/+1 for each other creature you control with a +1/+1 counter on it.
{3}{W}: Put a +1/+1 counter on target creature.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Jumpstart | 108 | Rare | $0.49 | — |
| Khans of Tarkir | 13 | Rare | $0.49 | $0.49 |
| March of the Machine Commander | 189 | Rare | $0.49 | — |
| Khans of Tarkir Promos | 13s | Rare | — | $0.49 |
2 rulings from Wizards of the Coast
- 20 September 2014High Sentinels of Arashin gets +1/+1 per creature, not per +1/+1 counter. It doesn't matter how many +1/+1 counters are on any other creature you control as long as there's one or more.
- 20 September 2014The activated ability can target and put +1/+1 counters on High Sentinels of Arashin itself.