There's some open source versions of this! Looked into it when I had the same reaction over the price lol

github.com/ambercaraval...

github.com/elegantalche...

OMG I had to email this NOAA researcher to be like, what's this .rex file things you're using, it's not documented anywhere, and he was like I named it after my dog Rex

Because the dog was big and the files were about big hurricanes