bare minimum:
mics >
cables >
recorder (+ some way to power this)
Tape mics somewhere, plug in, press record.
actual minimum list:
mics, mounts, bar for mounts, stand to put mics/mounts/bar on, battery box or preamp to power mics, cables to connect mics to bb/pre, recorder, more cables to connect bb/pre to recorder and somewhere to stash everything thats not in the air. Easy to do under 500.