Two notes: First, the term "genius" is difficult to define. Someone may be a "genius" at understanding the sociology of sub-Saharan African tribes, but this skill will obviously command a much lower market value compared to someone who is a "genius" as a chief executive officer of a large company. A more precise definition of genius will narrow the range of costs per year.

Second, and related to the first, MIRI is (to the extent of my knowledge) currently focusing on mathematics and formal logic research rather than programming. This makes recruiting a team of "geniuses" much cheaper. While skilled mathematicians can attract quite strong salaries, highly skilled programmers can demand significantly more. It seems the most common competing job for MIRI's researchers would be that of a mathematics professor (which have a median salary ~88,000$). Based on this, MIRI could likely hire high quality mathematicians while offering them relatively competitive salaries.