To my knowledge, you can buy DIX only with NXT.
So first by btc, ethereum LTC, on shapeshift you can exchange these coins for NXT coins . These next coins , store them in your wallet on mynxt.info.
There you can buy DIX. But you have to buy a plugin of 50NXT (=5$) to be able to buy DIX asset
Cheers,
You can also buy Dix asset at
https://stocks.exchange/ . open your account and transfer NXT coins to your NXT wallet. then buy DIX from NXT . you can store DIX coins using stocks exchange online wallet free of cost instead of spending 50NXT to buy plugin at mynxt.info.
only two markets available for DIX so far ( mynxt.info & stocks.exchange ) . you can decide either one as per your wish
you can get more updates on Dix asset by following below thread.
https://bitcointalk.org/index.php?topic=1696659.0