I mostly agree but the $100k is only launch cost, it doesn't include the engineering and manufacturing of the satellite or the ongoing operational costs.
$100k would only hire a single employee, it wouldn't even cover getting them into the field let alone setting up and maintaining infrastructure over the course of a year.
It's possible to reduce this number by taking advantages of labor conditions and goodwill, but that turns out to be a ton of legwork if you want a reliable team in the area year after year.
For example, in an anthro field school you might source local labor by identifying people who want to learn about their ancestors, and you'll expect a lot of community outreach and Q&A sessions around what you're studying.
You could attempt a similar approach for studying methane but I'd personally expect the Q&A sessions to include a heavy undertone of "convince me we shouldn't just kill the people involved", and all of my arguments against would be from the perspective of a system they don't really give a shit about. I'd certainly never put myself in that position.
