I would try 'The Flag Dude'. He has many images for the WSS and if he doesn't have the one you want but you can provide him a picture of what you need he'll make you up one. I would pay the extra for his
'cloth' flags. I'm putting them on all of my WSS units plus I order my flags that are more for a 40mm figure so they are a bit oversized but he can make them pretty much in almost any size you want. Each of my flags costs me 10
(USD) but I think they are worth it. Each flag will come with it's own pole and finial but you can order them without that if necessary but the price doesn't change.
He'll be at
Salute so if you can make it then stop by and talk with him. If he's got one of his 54mm ACW cloth flags, take a close look at it. The colors are incredible. Tell him I sent you! Ok, maybe that's not a good idea.