Seems expensive. I can imagine this being valuable if you needed a mobile darkroom, but expensive for testing out whether or not you like playing in the darkroom.
Can you maybe drape a couple of curtains, even temporarily, in the space you would plan to pitch the tent? I actually looked at these some time ago when I was planning on creating a darkroom, but it turned out to be very easy to darken the garage sufficiently (at night, at least). But I'm just dipping my toe in the fixer at the moment too.
If you are taking over a bedroom then water is a bigger issue than light, I suspect. I was lucky enough to exploit existing plumbing that the previous occupants had installed to run a washing machine.