Hi Andrew. I buy color neg. only in 5"x4". I'm just trying out a 10 box of Ektar 100 and a 10 Box of Portra NC 400 but my usual film is Portra VC 160 in large boxes. I have been buying from Badger Graphics and in lots of 200 sheets to minimise the shipping per sheet.
I am nearly ready to make another buy of 100 or 200 sheets, I hope you're selling when I'm ready to buy.
Kodak and Agfa have both stopped selling C41 color neg. development chemical kits in AU and the other manufacturers prices are a joke. I have imported individual dry chems. and make up my own solutions. Perhaps you can arrange an alternative.