These devices don't transmit. It requires personnel to be feat on the ground to collect SD cards. Plus the programming etc, can be done in house. I just need some directions on the hardware needed to achieve this.
I was thinking...
Rugged Sound Shield
Tell me if I am missing something?
Your budget needs to go on the microphone and a good low-noise preamp first, that's
perhaps $100 before you start even considering how to capture/store the data. An
Uno isn't up to handling the datarates involved, nor storing them to SDcard.
The Due is faster, can handle USB hosting so would I presume cope with recording
to a USBdrive.
Microphone is an issue, you are probably limited to high quality dynamic insert,
since electrets won't cope with damp conditions. You need a good low-input
impedance low-noise mic preamp, and then some sort of variable-gain or AGC
processing to prevent clipping. Then a I2S ADC is a good idea (cheapest part!), for
which there is a Due driver it seems: https://github.com/delsauce/ArduinoDueHiFi