It's no surprise that the Theta's design is being copied by low-cost 360 cameras. Here's one of those clones.
- two 210 degree fisheye lenses
- f/2.4 aperture
- fully spherical field of view
- Photo resolution: up to 3008x1504
- Video resolution: up to 1920x960 30fps
- uses a Micro SD card up to 128GB
The manufacturer claims that it can also record at 4k 24fps although I highly doubt that. I also doubt the 1.5 hour recording time.
I don't know the retail price or availability, but the wholesale price is under $100.