It's ridiculously expensive.
You can DIY one for less than $20:
https://dev.to/wassimchegham/build-a...han-20min-5h01
or
https://www.instructables.com/10-DIY...t-Works-Great/
There's multiple DIY tutorials, so feel free to find one that suit your needs. There's a little bit more expensive ones with a one-way mirror film.
I made one from a cheap image frame and with a piece of black cloth. For home made usage, there's no difference comparing to any professional teleprompter.