I would agree that if PACU time doesn't matter, gas doesn't really matter either.
I think the cost angle is way overblown. Desflurane run at under 0.5 lpm fresh gas flows is inexpensive. Isoflurane with low flows is even less expensive than that, but it's the difference between $1-2 per MAC hour and $3-4 per MAC hour. They're both so cheap that it doesn't matter. Cost is lost in the noise of everything else we do for anesthesia, and that's not even considering the cost of everything else in the OR.
ETTs are a lot cheaper than LMAs, but no one looks at you funny for using a LMA.
Vecuronium is cheaper than rocuronium, but no one looks at you funny for using roc.
It's just odd to keep hearing the cost argument for using isoflurane.