Seen Campy posts in this size as well as fair few NOS, 2nd hand and even new ones (St Johns Cycles has some in stock for example). I know Kalloy and others have cheapo posts in this size. But you'll have to be pretty patient to find something a little showy.
26.4mm is weird but not that weird. (ie http://www.sheldonbrown.com/seatpost-sizes.html
Seen Campy posts in this size as well as fair few NOS, 2nd hand and even new ones (St Johns Cycles has some in stock for example). I know Kalloy and others have cheapo posts in this size. But you'll have to be pretty patient to find something a little showy.