The reason that Crytopia's market is higher than the other exchange is because the wallet is in maintenance. This prevents new coins entering their market. Also, people are prevented from using arbitration. Once the Cryptopia market comes back online, it is likely to go back down as all of the fresh coins hit their market.
yup..they have this maintenance on the wallet for quite a while now. i think that is more than 2 weeks since it is impossible to put coins into their exchange.