These folks stock several species other than badger that are smaller and might make an adequate but smaller sporran:

http://leatherunltd.com/furs/natural/natural.html

I've been wondering what the muskrat looks like and for $20, I might just order one to see.

I get your point about the general huge-ness of some of the full-critter sporrans...sometimes it looks like the sporran is wearing you instead of you wearing the sporran.

I'm sure that when you find a pelt supplier you could call them and ask if they have any smaller versions of what you're after.

Best

AA