For snows I would suggest:
Inexpensive- Grounds, Primos, Tru-tone, but the Tru-tone is not as loud as the others
Middle- Mann Express snow
Acrylics- Mann, Grounds or Foiles
I am sure that there are others that sound good, and I have found some that I do not think sound so hot. However, I have had great personal experience with all the above calls...wish I owned them all!
Not sure of any videos or tapes for snows, but the calls are easy to blow and learn. May check out Huntingsnows.com and see what they have to offer.