The idea of using soft bags for the storage of developer is quite attractive. 3 and 5 liter containers are extremely cheap:
http://www.rekru.de/index.php?cPath=Bag-in-Box-482

On the other hand they are made of PE. And PE is relatively well permeable to oxygen. Does anybody have experience with storage of developer in PE?

Alternative there is also the “Accordion Bottle” from Kaiser.

http://www.kaiser-fototechnik.de/en/...ge.asp?nr=4198

Chris