Exchange your duplicate stamps for those you need based on Scott's catalog value. Once you enroll, purchase blank Omni books (3 for $1), mount your stamps entering Scott's catalog value and current value, and send them off to the appropriate Omni manager. Your Omni account will be credited in the amount of material you send in. In return, you can choose stamps submitted from other members. When your books are retired, they'll be returned to you minus return postage costs and a 10% exchange fee. Your account balance is always updated as needed.
This program is currently available to USA and Canadian members at the present time.