Cheapest priced copy (Zendikar): $0.39 at Card Kingdom, near mint, their price list as of .
Khalni Gem 
Artifact · Uncommon · Zendikar · #205
When this artifact enters, return two lands you control to their owner's hand.
{T}: Add two mana of any one color.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.39 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Zendikar | 205 | Uncommon | $0.39 | $2.49Out of stock |
One ruling from Wizards of the Coast
- 1 October 2009If you don’t control any lands by the time Khalni Gem’s triggered ability resolves, nothing happens. If you control just one, you’ll have to return it to its owner’s hand. Khalni Gem isn’t affected in either case.