I wanted to buy some Eco but wasn't sure how to do it so I followed this post from @riverflows for buying LOTUS coins but you can use it to buy any coins.
https://steempeak.com/naturalmedicine/@riverflows/how-to-trade-lotus-or-any-other-token-in-steem-engine
I followed the instructions and bought my ECO
I did use Steemkey and have saved my active key there
Hope this helps and good luck buying some ECO!