The production team reportedly covers the flights, two nights in a hotel, and $5,000 in cash to compensate for lost wages, as per Nicki Swift.
As casting director Kristi Russell explained in a previous interview with Channel Guide Magazine, some contestants also receive training before being sent to a mystery location with only a radio transmitter and a bag to see them through three weeks’ worth of intense mental and physical challenges.
Source: https://www.distractify.com/p/how-much-do-contestants-make-on-naked-and-afraid