Yes, per volume, Bleach III is cheaper. The issue is that I don't need 100 liters of bleach nor do I want to spend $165 on the two parts. I just don't do that much C-41. If you know of a cheaper source or smaller quantities, please let me know.
If the RA process bleach works just the same and is no less archival, then it might be a better fit for me. It still makes five liters, which isn't exactly scant.