I have used Yesterdays News litter at the shelter forever.  It keeps the
smell down, its safe for the ferrets.
 
Petsmart sells 30 pound bags for $12.99. It is in the cat litter section.
The folks at Y.N. are great, they send me a voucher for a free bag of litter
when I send in 7 upc codes. They have also been kind enough to help me
out with free litter when times are tough.  Any shelter can get on this
program.  They also sent me dollar off coupons which I give to adopters.
They will send you samples to give out.  It is a ferret frendly company
with great folks working there.  Just thought i'd put my 2 cents in on the
litter discussion.  CJ 24 Carat Ferret Rescue And Shelter
[Posted in FML issue 3579]