I agree that a proper sporran is best for wear with a modern kilt, which is why I made sure to buy one when I bought my kilt from Rocky. But when it comes to costuming, such as ren faire garb, there's room for some leeway. My profile pic shows the highland garb I wear to the PA Ren Faire. The "sporran" is actually something I found on a Goodwill store purse rack many years ago. It's composed of a leather front piece, back piece/flap and gusset, with a leather thong thats loops around a piece of antler for closure. The strap is braided leather that looks exactly like a modern braided leather sporran belt. I cut slits in the back to thread the strap through, and it has served me well for years.

Granted, I was very lucky to find something that was constructed very much like a rustic sporran, and required very little conversion... I would not have attempted it otherwise. The purse in the OP's pics just doesn't seem rustic enough.