Any thing will work. I have used buck tail, kip tail, alpaca hair and synthetic hair. It all works well. Buck tail seems to fall a little slower. The only thing that I have never tried is bear I hear it is the best.
Use a good nylon thread or outdoor type of thread and you will be fine. I also like to use a little clear finger nail polish on the wraps to help keep them in place.
The best place to buy it is off the Punisher web site.