I would not mind, to pay back $ 99 for the NGUI version for Unreal4. I tested the "UE4" and this very good, the level of ease to work with it, is very close to Unity. Very good.
ArenMook, have a topic on the Marketplace area on Unreal forum, the creator of the Suimono Water plugin, posted there asking if people might want him to do a version of the Unity plugin for Unreal, and was well received.