.FIT is one of the hundreds of new extensions.
Nice combinations can sell in .fit as namebio.com shows, but as it is a narrow extension, there are only a few good combos (disregarding GEOs, or existing fitness brands).
Boss fit can serve as brandable, and as such can fetch imo 2-3k for ideal end user (quick google search shows that there are actually some companies in fitness industry using "boss", so those could be your end users)