Literally the top grade of beef for the top cut.
Of course it's $39/lb.
It's not just Key West.
Btw - your typical cut at the grocery store is Select
https://www.usda.gov/about-usda/news/blog/whats-your-beef-prime-choice-or-select
https://www.webstaurantstore.com/blog/4832/best-cuts-of-steak.html