Quality Sporrans for less money

[gun eagal]

This epic thread is like a graduate course in sporrans. Thanks very much. I've learned quite a bit.
Here's a question I've had for a long time but it may be out of place here. I'm new to the forum, so please move it if necessary.
I've noticed a lot of sporrans that are made with pigskin, or cowhide stippled to look like pig skin. In leather bag making pigskin is most often used as a lining. On sporrans the pigskin is often laminated onto the back of a piece of cowhide for structure. Why is pigskin used so often? It's very tough, but kangaroo is tougher. Is pigskin just tradition? If so, how far back does the tradition go?
many thanks
John