Power window "regulators" (the unit that holds and raises/lowers the window) are usually similar in price and weight to cranked manual window assemblies, and can be cheaper. A small motor is not at all expensive and is a less specialized item than a window crank handle and gear unit.

What could save money is not needing to run any wiring whatsoever into the door - if the doors can be made with no speakers, lighting, crash sensors, switches, power locks, or power windows, then the assembly becomes significantly simpler and therefore cheaper since there's no wiring harness to fish (usually a manual production step), no holes and grommets, etc.

But if power windows are going to be an option, I'm not sure how this plays out. Do the power windows come with a wiring harness that requires the user disassemble the interior and fish the wiring? If it comes pre-wired, then the choice for manual windows is actually quite strange and possibly more expensive.