There are lots of options for a packable tandems, not just Bike Friday. Co-Motion and Santana make packable tandems that use standard sized wheels, both 26 inch and 700c. I suggest you look at those.
You might also look for dealers that carry used packable tandems if you are looking for a lower cost machine. I can suggest Mt. Airy Bicycles in Mt. Airy, Maryland. They have a fairly large inventory of tandems and they are also Bike Friday dealers (along with College Park Bicycles, their sister shop).