Cheapest priced copy (Magic 2013): $0.69 at Card Kingdom, near mint, their price list as of .
Ring of Kalonia 
Artifact — Equipment · Uncommon · Magic 2013 · #212
Equipped creature has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's green.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.69 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Magic 2013 | 212 | Uncommon | $0.69 | $3.99 |