If you pay for a good transcoding service, you're not just paying for being able to run FFMPEG. That's the easy part. The hard part is dealing with thousands of combinations of audio and video codecs, containers, pixel and display aspect ratios, handling improperly encoded files and optimizing to produce the best quality at a given size. There's a reason entire companies are based on being good at these things, and people are willing to pay for it. This is not trivial stuff.
I'm not knocking the PiCloud product at all, as there are certainly some limited use cases where it would fit nicely and get the job done cheaply. But it is in no way an apples-to-apples comparison between a generic FFMPEG setup and a professional encoding service like Zencoder or Encoding.com.