I have bought all of my moss, aspen and cypress at the local pet store. Im not sure what you have in your area, so I would suggest calling around to all the pet store around you, or shopping online and have it delivered depending on when you need it.

Cypress will hold the humidity better than aspen. It is not necessary to use cypress to obtain good numbers though. I use aspen and my numbers are pretty constant.

What kind of humidity problems are you having? What kind of set up do you have right now and what kind of maintenance are you doing? What are you numbers looking like right now? Are you increasing the humidity so a shed cycle? Are you finding the humidity is dropping to fast?

Once you give some more information, Ill be able to help out more. Cheers!