Get the Rokinon/Samyang. Look at previous cine versions of the rokinon/samyang lenses. You could get a an earlier "model" for much cheaper. Although they may lack an aspherical element or lens coatings, that's what can give your images some "personality."
Also look at other mounts for the lens if you need to save money. The ability to adapt virtually any lens on your Sony via an adapter opens up the world to all kinds of glass. :)
Nikon lenses are designed for a very long flange distance. So if you ever chose a new camera brand, you could possibly adapt a nikon mount lens to that body too. And a nikon mount rokinon/samyang lens is usually cheaper because of Nikon's lack of video features.
Keep in mind that the rokinon/samyang lenses are all "manual" lenses. You will not have autofocus, or an automatic aperture. If you can't live without those features, then maybe the other lens will be worth it for you.
Shooting manual only does good things for you though. It forces you to slow down and compose your image.
Hope this helps!