How to consolidate dust transactions in 2017?
Just now (July 2017) the mempool is down, which allows for small fees.
Usually fees are created by the size of the transaction. With lots of dust, a transaction will have many inputs, and increase in size. That increases the fees. 
I have seen transactions with low as 5 satoshis per byte. So it's a good time frame. 

Similar reply here:
Why was the transaction fee more for a 20 mBTC transaction than for a 25 mBTC transaction?