Cheapest priced copy (Eighth Edition): $0.49 at Card Kingdom, near mint, their price list as of .
Solidarity 
Instant · Common · Urza's Destiny · #20
Creatures you control get +0/+5 until end of turn.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.49 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Eighth Edition | 46 | Common | $0.49 | — |
| Eighth Edition | 46★ | Common | — | $2.49 |
| Urza's Destiny | 20 | Common | $0.49 | $1.99 |