There were actually two separate Koko sets. The originals (in the 5-1000 denoms) were made by BR Pro; those are the ones from the 2005 date you mentioned. The group buy at Chiptalk were for the add-ons that were made by Brent at Lynbark Designs (via ABC).

This is the set in its entirety, with the top two rows being the add-ons, the bottom two, the originals: