I know you're looking for a Calfee yet yesterday there was a posting of a Santana Beyond (appears to be a medium/small) on the tandem@hobbes list. I thought I'd mention it because premium tandems don't pop up on the used market often (as merlinextralight has said). We looked for a coupled Santana Team Scandium, Team Ti, or Beyond for 1 ½ years before pulling the trigger and ordering one.

Tailwinds,
Charlie