I bought a "lot" of three or four soft tank bags and saddle bags a few years ago that were missing the straps and buckles. Frankly I don't know how I got along without them before. (I made new straps and fitted buckles to them.)
The tank bags I have are an Eclipse, An RKA, and a couple others I don't recall brand, saddlebags are Fieldshear (sp).
I recall the RKA is expandable and is probably my favorite, even if the zip off side expansion bags are missing. The Eclipse is nearly as nice and gets the most use along with the RKA.
They either have a firm foam base or a rather thick fur to protect the tank, and have quick clip buckles and straps to hold them on and make it easy to tote away with you. Most have a map pocket for the top. Old school perhaps in these days of GPS, but it works well with maps or written instructions. (We are still allowed to write with pen and paper, aren't we?)
Not quite the storage capacity of a Goldwing. But, it gets far closer.