Cheapest priced copy (Foundations Jumpstart): $0.35 at Card Kingdom, near mint, their price list as of .
Breaching Hippocamp 
Creature — Horse Fish · 3/2 · Common · Theros · #43
Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, untap another target creature you control.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations Jumpstart | 290 | Common | $0.35 | — |
| Theros | 43 | Common | $0.35 | $0.49 |