Mercatox was working fine for DSR last week, I imagine it will be working again soon.  If you scroll through the deposit list on Merc, you'll see that there's a dozen other coins that say not available (including Steem). 

Coinexchange.io is a decent exchange, I hope DSR appears there soon.  I'm not sure how much Kucoin charges but thats a much hotter exchange imo, their growth is going crazy especially now that Binance isn't accepting new peeps until they upgrade their platform.