I've sold my Strom so have a used FAMSA tank bag on my hands. Its specific to the 2004 - 2011 Strom, mine was a 2006 DL1000 (I think it also fits the 650 of the same era). Brilliant bit of kit, showerproof but has a waterproof cover, expandable, and sits really tight and stable on the Strom tank on a harness which means no scratching of your tank every time you take it off to refuel.
£40 to a good home, will post it subject to agreeing cost.