There are quite a few brand name metal panniers out there as aftermarket bags. These are mostly  good but they are also expensive -- close to $1,000.

I began making custom motorcycle seats 20 years ago -- my first one was for my 1986 K75.

A custom saddle makes all the difference in the ride for me. A good saddle in leather can run you about $300 - $700 US, but worth every penny.