Cheapest priced copy (Modern Horizons 3): $0.35 at Card Kingdom, near mint, their price list as of .
Hexgold Slith 
Creature — Slith · 2/1 · Common · Modern Horizons 3 · #30
When this creature enters, you get {E}{E} (two energy counters).
Whenever this creature attacks, you may pay {E}{E}. If you do, it gains first strike until end of turn.
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 3 | 30 | Common | $0.35 | $0.49 |