Cheapest priced copy (Outlaws of Thunder Junction): $0.35 at Card Kingdom, near mint, their price list as of .
Cactarantula 
Creature — Plant Spider · 6/5 · Common · Outlaws of Thunder Junction · #158
This spell costs {1} less to cast if you control a Desert.
Reach
Whenever this creature becomes the target of a spell or ability an opponent controls, you may draw a card.
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Outlaws of Thunder Junction | 158 | Common | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 12 April 2024If a spell or ability targets Cactarantula more than once, its last ability still triggers only once.
- 12 April 2024Cactarantula still costs only {1} less to cast if you control multiple Deserts.
- 12 April 2024Cactarantula’s last ability resolves before the spell or ability that caused it to trigger. It resolves even if that spell is countered.
- 12 April 2024Once you announce that you’re casting Cactarantula, no player may take actions until the spell has been paid for. Notably, opponents can’t try to change whether you control a Desert.