For sale, Nelson-Rigg saddlebags model SSC-140. Brand new, tags still on, never on a bike but have been sitting in the garage for a year. In very good condition (I'll post up pictures of them later). I'm looking for something larger, so no go for me. $70 shipped OBO.
They have two large velco straps and some quick release buckles. Depending on the bike you would put both under the seat or one under and one over (if both do not fit). They have decent padding to keep the paint unmarred. Sorry, I can't find my camera to give you a better idea, but will keep looking for it.
I haven't been able to find a good way to stick in on a 919, in all honesty.
PROPS for not BSing the guy to sell your wares. Speaking strictly of other sites.... this is stand-out behavior.
Good luck with your sale. Just a hunch but if you do post some pics I wouldn't be surprised if we find that mounting on the 919 is possible. Based upon your description they sound alot like my Cortech saddle bags.