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Unity3D is a very good engine that is real-time 3D and it has nothing to do with wme workflow.
The non-pro version of Unity is free (although it's a little limited compared to the pro version).But you are mixing things a little. Blender, 3DS Max, Maya etc. are 3D modelling applications, while Unity is a game engine. Game engines, such as Unity or WME are designed for bulding the game logic. But you still need some 3D modelling application to create the game assets.