Cheapest priced copy (Tempest): $0.99 at Card Kingdom, near mint, their price list as of .
Chaotic Goo 
Creature — Ooze · 0/0 · Rare · Tempest · #168
This creature enters with three +1/+1 counters on it.
At the beginning of your upkeep, you may flip a coin. If you win the flip, put a +1/+1 counter on this creature. If you lose the flip, remove a +1/+1 counter from this creature.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.99 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Secret Lair Drop | 1658 | Rare | $1.99 | $1.79 |
| Tempest | 168 | Rare | $0.99 | — |