Easily. Finding them loose is proving somewhat difficult after a brief search.
Yeah, at one time they were everywhere. Certainly DiD will use them again for some new Nazi figure. Matter of time.
Try to get some names of the figures that came with that satchel and check Toy Anxiety and Monkey Depot, they may have them listed by character name.
I found a black one on ebay: https://www.ebay.com/itm/1-6-DID-LEATHER-BRIEFCASE-BAG-ACCESSORY-DRAGON-DID-BBI-21St-WW2/322008840169?hash=item4af938f7e9:g:nsYAAOSwDuJWwRRB