In my experience, Machining cost is about a wash:
NPT = Pre-drill to minor thread diameter then tap - Tapping has to be done carefully as it's a tapered tap. Can't go too deep or too shallow or the mating fitting won't work
SAE = Pre-drill (less than thread minor diameter) then form tool then tap. All are high speed operations
You can get SAE form tools that will drill the rough hole, pre-drill all in one, but they're generally expensive compared to the additional machine time. He's not likely constrained by the machining time anyway.
The NPT tapping/inspection process is also much more controlled/involved than a straight thread port so that end of it typically cancels out any machining time advantage.
All of this may be irrelevant depending on how evguy1 has his process setup.
Fittings/adapters are a negligible cost difference - Can't seem to find the quotes now but they're within a few pennies on a fitting that is less than $2.00 regardless if you're going NPT to JIC, NPT to ORS, SAE to ORS, SAE to JIC, etc