I too have been considering having a few custom jerseys made. From a recent thread in the Road forum:

http://champ-sys.com/custom/cycling/jerseys

http://www.voler.com/custom/


Voler is currently selling their "try on" jerseys at a discounted rate and there is a coupon code for another 10% or so off. The link and code are also to be found in recent a Road forum thread.