I bought a couple duffle bags (10x10x17)  from Walmart for under $10 each.  With a razor blade, I cut out the inner floor liner, structural cardboard and unnecessary straps. 

They fit nicely in my saddlebags and make the task of loading/unloading my bike real easy. 

Andy

CleRider 

"Giving someone else equal rights does not take rights away from you...
  It just makes it illegal to enforce your prejudice and hate."