Cheapest priced copy (Fallen Empires): $0.99 at Card Kingdom, near mint, their price list as of .
River Merfolk 
Creature — Merfolk · 2/1 · Rare · Fallen Empires · #24
{U}: This creature gains mountainwalk until end of turn. (It can't be blocked as long as defending player controls a Mountain.)
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fallen Empires | 24 | Rare | $0.99 | — |