I don't know where you're seeing the < 10mb from the situation I saw they were easily consuming 30mb per interpreter. Even my cursory search around now shows them at roughly 15-20mb so assuming the 30mb Gunicorn was just misconfigured that's still an extra $100 per host using your estimate and what I'm looking at Googling around and across a situation where there are multiple public apis that's adding up pretty quickly.

Another google search shows me Gunicorn, for instance, using high memory on fork isn't exactly uncommon either.

Edit: I reworded some stuff up there and tried to make my point more clear.