For loose catnip, my cats love Cosmic. There are 2 toys they do really well with: the burlap "Catnip, 50lb" and Dr. Pussum's Fancy Feline Elixir. This comes from New England some place and is only available at cat shows. If you ever come to a cat show in the US, look for a merchant that sells 8 foot or 2.5 meter cat trees. They are the ones who sell this catnip that my kids go nuts over!

As far as shipping catnip, its unfortunate resemblence to contraband in the dry form my cause problems...