http://sancrypto.info/index/show/AUR/

Auroracoin has 11Ghash maintaining the blockchain.  11,000mhash protects $300M of supposed 'market cap.' 

11Ghash is not a lot of GPU.  There are scrypt mining pools that dwarf auroracoin (e.g. middlecoin has 15Ghash).  a large enough pool could take auroracoin for a ride and usurp the blockchain by mistake.  a small cartel of miners with malicious intent could inflict tremendous damage on the blockchain.

This vulnerability is shared by basically all coins except bitcoin.  

When figuring out what a currency is worth, the security of the blockchains should be considered.  if the blockchain cannot be sufficiently distributed, the risk of transaction reversals or intentional forks should destroy any value in that coin.   Because of this vulnerability most coins are overvalued.