jglass, it's that the first endeavor saves $3, the second, only 75 cents. Diminishing returns with great effort. Effort meaning perhaps buying in huge quantities and storing them.
I've been into photoraphy for well over half a century. It's my observation that many photographers get fixated on the costs. I can honestly recognize this because I'm guilty of it, too. If I buy film Brand X, I can save thirty cents a roll over Brand Y and probably get the same results. Or, buying bulk film instead of rolls. Oh, Lord, I've bought and rolled lots of bulk, all for that mythological several dollars a roll savings when I wasn't shooting very much.
I think anything under $3/roll for C41 processing is just fine, compared to the alternatives.
Mi dos centavos,