With the introduction of Booth, the mutie tattoer in Core City Sewers, he can sell you good and rare quality leathers.
I have noticed, with the magic of merchant refresh spam, that the range of quality of cave hopper he sells max out at 70
At the same time, I ventured into the Cave Hopper Graveyard and the leather drops there did not go above 70, or 65.
So, you can just visit Booth frecuently to get high quality hopper leather much easier and faster than taking a stroll throught the caves to the Graveyard.
This feels like a massive oversight. It is a shame because right now there's no reason to visit the Graveyard whatsoever.