Cheapest priced copy (Avatar: The Last Airbender): $0.35 at Card Kingdom, near mint, their price list as of .
Ostrich-Horse 
Creature — Bird Horse · 3/1 · Common · Avatar: The Last Airbender · #188
When this creature enters, mill three cards. You may put a land card from among them into your hand. If you don't, put a +1/+1 counter on this creature. (To mill three cards, put the top three cards of your library into your graveyard.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Avatar: The Last Airbender | 188 | Common | $0.35 | $0.49 |