Cheapest priced copy (Commander Legends): $1.79 at Card Kingdom, near mint, their price list as of .
Mask of Avacyn 
Artifact — Equipment · Uncommon · Innistrad · #229
Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $1.79 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 466 | Uncommon | $1.79 | — |
| Innistrad | 229 | Uncommon | $1.79 | $7.99 |
One ruling from Wizards of the Coast
- 22 September 2011If Mask of Avacyn somehow becomes attached to a creature an opponent controls, that creature can't be the target of spells or abilities you control.