Cheapest priced copy (Innistrad Remastered): $0.35 at Card Kingdom, near mint, their price list as of .
Gryff's Boon 
Enchantment — Aura · Uncommon · Shadows over Innistrad · #20
Enchant creature
Enchanted creature gets +1/+0 and has flying.
{3}{W}: Return this card from your graveyard to the battlefield attached to target creature. Activate only as a sorcery.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.35 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 67 | Uncommon | $0.39 | — |
| Innistrad Remastered | 25 | Uncommon | $0.35 | $0.49 |
| Innistrad Remastered | 342 | Uncommon | $0.39 | $0.79 |
| Shadows over Innistrad | 20 | Uncommon | $0.39 | $0.99 |
One ruling from Wizards of the Coast
- 8 April 2016If you activate Gryff's Boon's last ability and the target creature becomes an illegal target in response, the ability doesn't resolve and Gryff's Boon remains in your graveyard.