What type of travel nurses make the most money?

Does a travel nurse with some type of Masters degree make more than just one with an RN? I know there are websites out there saying CRNA's make over 0 hr. traveling. I'm not sure about entering the CRNA program, only because it's so rigorous. How about Acute Care Nurse Practitioner, or Mental Health. Any ideas how much they would make traveling? Also, any website links would be greatly appreciated. Thanks!

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