It's funny you said this, those hoses are one of my pet peeves. HD and Lowes only sell one replacement and it is a plastic coated stiff hose and to top it all off barely any water comes through.
I like to actually get wet in the shower and not fight with the thing. I didn't have any luck finding a decent one separate but one day I found a closeout shower head on the shelf at HD. It was missing parts but had a great hose, so I bought it.
About a year later when I was in China I noticed there is no flow restriction on their shower heads, the hoses were great and flexible. That day I stopped at a local hardware store and they had every length you could think of. Here in the USA they limit the flow rate as well as length for safety, China... Na who cares
So I bought a case of them to replace and have spares. I have replaced 3 at home, and the two on the TT.