Canon makes two more of these 50 primes as well, the f/1.4 and the f/1.2. The f/1.4 is about 300-400 dollars and the f/1.2 is a whopping 1000 dollars. The price changes with these three lenses are based on two main factors, the f-stop and the durability. The awesome thing about these f-stops is that with such a low f-stop low light shooting will be easier as well as getting that desirable BOKEH effect that makes your photos and video look awesome. The f/1.8 has been said to be almost like a toy in the way it feels, the whole lens is made out of plastic for the most part, while the other two have metal mounts and the f/1.2 is even weather proof. While these minor differences in stop and build are somewhat noticeable whats the picture quality difference.
An article on F Stoppers is what sparked my recent interest in these prime lenses and they have an awesome article that talks about the three lenses and again the best bang for your buck if your pinching pennies is the f/1.8. These two sources talk about the photography portion of these lenses a lot so I plan to do more research and learn a little more about the video aspect of these lenses before I go spending my hard earned cash. Its looking like relatively soon I will invest in a prime because these deals are something I just can't resist.
Here is the link to the article definitely check this out quickly if you don't have the time for the video. But if you do I definitely recommend you look at both.