ICANN has lots of rules around TLD assignment, so squatting .gov doesn't seem possible. But some have recurring cost. Here's gTLDs:

> a fixed fee of US$6,250 per calendar quarter; (b) and a transaction fee of US$0.25. [1]

.gov is not a gTLD, I'm not sure what financial relationship exists, if any.

[1] https://newgtlds.icann.org/en/applicants/global-support/faqs...