Cheapest priced copy (Adventures in the Forgotten Realms): $0.35 at Card Kingdom, near mint, their price list as of .
Bull's Strength 
Instant · Common · Adventures in the Forgotten Realms · #174
Target creature gets +2/+2 and gains trample until end of turn. Untap it.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Adventures in the Forgotten Realms | 174 | Common | $0.35 | $0.49 |