Yes, I think you're correct. Thunderbolt is a patented technology created by Intel, and if you want to add a Thunderbolt port into your new device, you need to get a license or even a special part/board from Intel.
I wouldn't call BizonBox a copy of AKiTiO. It is essentially a "package" that includes:
AKiTiO Thunder2 enclosure;
videocard, which they can install for you into the enclosure;
power supply, NOT made by AKiTiO or Bizon;
manual - written by Bizon - but it requires you to install open-source software developed by other people.
So Bizon did not invent anything and you can certainly build it yourself if you want. I just didn't have time for that.
My recommendation: save up for a faster Mac, e.g. iMac 2015. This is what we did. I don't know about Blender 3D, but Photoshop doesn't need a very fast GPU. It also depends on what effects/filters you use most often. Some filters do not benefit from a faster GPU at all.