Bob Cunico writes:
I am looking for advice for purchasing a recording system for voice
and natural sounds. The most important features are cost $300, must
be portable, and as high a frequency range as possible (20-20kHz would
be ideal).

People who are into recording nature sounds for scientific purposes
don't want to use any recorders that apply psychoacoustic audio
compression. That would disqualify the Tascam PS-5 that you mention
since it's an MP3 recorder. They'd rather use an analog cassette
recorder even if the frequency response isn't so tremendous. The
Creative Nomad 3 Jukebox (note the "3", not earlier models) can record
in uncompressed WAV format so that's considered ok for them. I don't
know if this issue applies to your application. You will need to use
an amplified mic or mic preamp.