There are always alternatives. :)
I bought my last headphone cushions at K55.

Here is the original from Bose:
https://www.k55.ch/bose-ohrpo...

I got the slightly more expensive version:
https://www.k55.ch/dekoni-aud...
In my opinion, it feels more comfortable, but after a good year it is starting to show signs of wear (small cracks).