You can get them from Cedar Sole LLC in Fort Worth, TX. 1-800-536-0041. Ask for Peter O'Brien
Just buy them online... search for cedarsoles! There are several inserts on the market. I've tried Zederna Cedarsoles and Cedrinas.
Zederna Insoles made from cedarwood are probably the best absorbent insoles for sweaty feet. You can buy them online on www.zederna.com. Just do a short web-research.