The Elephants are awesome and appreciate quickly. Grab remaining 2013 for as cheaply as possible while some of the bigger retailers are selling the last of their stock. You can still get one for $30 but once the retailers run out it'll be a $40 coin. There's plenty of time to accumulate 2014s.
I just completed the BU set (2004-2014). 2004-2008 have the lowest mintage and are quite rare. They are appreciating rapidly.
I just purchased the above mentioned two coin day and night colored Elephant set. Only 500 minted and the ONLY way to acquire the "day" coin. The night coin can be purchased separately. I would imagine (hope) that with such a low mintage the 2 coin set makes a great investment.
Next I will begin collecting the proofs, gilded and colored coins. Official mintage numbers, since 2010, for each these coins is 5000.
I collect mainly as a hobby but also as an investment. I collect a wide variety of world coins and enjoy each one for their beauty, history and uniqueness.
Besides a handful of other specific coins I haven't found a modern series that would make a better investment than the Somalia Elephants. I love Pandas and own several but the Elephants appreciate a greater amount and their minting Pandas into crazy high numbers.
For a pure bullion play I love Libertads. They might not be the best deal but that's one sexy woman on the face of that coin.
Cheers!