You have pretty good renders engines inside Blender who are entierely free! Blender too!
The only cost is the learning curve who is not so evident for my old brain! :)




So I prefere Fusion 360 (free for enthusiast,hobbyst, student, even StartUp ! http://www.autodesk.com/products/fusion-360/try-buy
who has a render like a sort of an easy Keyshot for mecanical volumes or other crazzy forms! Life is too short! :)
And works very fine with Moi :)