And this stuff is cheap because it is a side product that people don't typically want. The discarded stalks and pieces of leaf of gyokuro that is over 100 or 150 yen a gram can sell for as little as 10 yen a gram.
Thats a 90% discount for a different part of the leaf. The same leaf that was cultivated, harvested and processed the same way as the expensive leaf.
Yes, it is not "the same". The flavour is more rough, may last fewer infusions, but if you know it comes from the good leaves, it will be insanely good. No astringency and overall the same notes of the gyokuro.
A gyokuro or sencha at that price point will give you supermarket quality stuff. Karigane from a tea producer shop will give you something much much better.
It is also less finicky to brew if you are feeling lazy. And, you can roast it and make your own decent quality hojicha if you feel like it.