Hi Scott,
Its good to see another Aussie collector. We are 
unfortunately a rare breed.
Anyway, regarding your question - I have found 
the A3 Colby Art Display Books quite suitable for 
keeping cels. Just make sure they are the acid 
free version. I believe they all are but am not 
completely sure.
You can pick these up at pretty much any art 
store. I'm in Sydney and get them from Eckersleys 
art stores or even Dymocks in the city.
Hope this helps.
X