Cheapest priced copy (Ultimate Masters): $4.49 at Card Kingdom, near mint, their price list as of .
Daybreak Coronet 
Enchantment — Aura · Rare · Future Sight · #21
Enchant creature with another Aura attached to it
Enchanted creature gets +3/+3 and has first strike, vigilance, and lifelink. (Damage dealt by the creature also causes its controller to gain that much life.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $4.49 to $22.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Future Sight | 21 | Rare | $7.99 | $22.99 |
| Modern Masters 2015 | 14 | Rare | $5.99 | $6.99 |
| Ultimate Masters | 14 | Rare | $4.49 | $6.99 |
| Wilds of Eldraine Commander | 65 | Rare | $4.49 | — |
2 rulings from Wizards of the Coast
- 1 May 2007If all other Auras attached to the enchanted creature stop enchanting it, Daybreak Coronet will be attached to an illegal permanent and will be put into its owner's graveyard.
- 7 December 2018If multiple Auras are entering the battlefield at the same time, you choose which player or permanent each enchants before any of them enter the battlefield. This means that Daybreak Coronet can't be put onto the battlefield enchanting a creature that's not enchanted before the Auras all enter the battlefield.