I would love to use a live model, but the hubby doesn't look good holding a purse (they are not manbags - haha!).
I did use a co-worker to model my first bag on Etsy, then realized that she is less than 5 feet tall and 85 pounds soaking wet, so the bag looks enormous!
I would find a very nice, old wooden ruler, a vintage cigarette lighter (but the BIC is found everywhere), a #2 wooden pencil, a CD case, or your business card, depending on what you are selling. I think that all of the above mentioned are fairly standard in size and availability worldwide.
You'll still get convos asking about size, color and everything else.