No "normal" self-respecting woman would pay $6000 for a bag. On the other hand, an abnormally rich woman with nothing better to spend her money on, would buy one. I personally hate Birkin bags. I wouldn't spend so much money on something so ugly. Most women I know agree with me. The women I know are "normal." I certainly wouldn't mind my husband saving up for a very nice sporran though, but he would rather settle for one of the cheaper ones.
Now, once it becomes much more of a fashion statement for the average American man to own and wear kilts, more ritzy, expensive sporran shops will open. Right now, there are more rich women with incredible amounts of money in the USA who decide to spend their money on stupid expensive ugly bags than there are rich kilted men with incredibly amounts of money who decide to spend their money on expensive sporrans. That's why there's a larger market for expensive handbags that there is for expensive sporrans. I don't want to step on any toes, but that's how it is right now. Hopefully, it will change in the future.