Interesting gadget but not something I would buy even if the price tag listed it at $10.
I make all the bread products in our house and have done so for longer than I can remember.
My proofing box is the microwave. All I do is put a cereal bowl of water into the microwave and heat on HIGH for 4 minutes. I do this a few minutes before the dough goes in. The inside of the oven becomes warmish and humid.
Put the dough in (leaving the bowl of water inside, too), close the door and let the dough rise. The oven easily stays warm for an hour.
To quote Alton Brown, "The only unitasker device/tool in the kitchen is the fire extinguisher."
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!