I'm obviously a cheapskate. I swapped my wool blend shirt (intended as a mid-layer for the late winter start of my through-hike) for a used PrimaLoft (polyester fill) vest. When I adjusted from short-sleeve wicking tees underneath to long-sleeve, my winter clothing total was 5 oz. less for $20 spent ($4 per ounce saved).
Details are important here.
While ZPacks packs are light, their cost model quickly ruins your savings unless you really want a plain bag. Here's what it would cost to have the same features as my $159.49 Granite Gear Crown 2 in a ZPacks Arc Haul: $299 base price + $45 belt pouches + $10 ice axe loops + $10 roll-top closure straps + $10 v top strap + $15 lumbar pad + $45 spare belt + $10 shock cord lashing = $444: that's roughly 3X what I paid. (Plus ZPacks only makes their belt pouches in black, which is a stupid choice. Who wants their chocolate snacks melted in the sun?) The ZPacks configuration would be 6 oz. lighter for that $284.51 price difference ($47 per ounce saved).
Of the included standard features of the Crown 2 pack, I'll be using all of them on the AT except for the ice axe loops. (And those may come in handy later on the PCT. )
So an ounce is definitely worth $4 to me, and definitely not worth $47.