In DragonVale for the Android & iOS devices (iPhone, iPad, etc.) the Lunar Eclipse Dragon (like the Solar Eclipse Dragon) is a limited dragon in which the availability is somewhat unknown, since a lunar eclipse can happen around the globe at any time. Keep an eye on the market, and if you see it available to purchase then you should be able to breed it.
The Lunar Eclipse Dragon has a base breeding time of 48 hours, sells for 2,250,000 coins, and earns 100,000 XP for successful breeding once you reach level 14.
To breed a Lunar Eclipse Dragon, you need to breed dragons that have a mix of air, cold, and earth elements. Sandstorm + Cold seems to be a popular combination.
Need lots of gems at a cheap price? You can actually buy DragonVale gems on Ebay.