Most expensive microphone includes Earth works SR-30 Matched Pair. Quite simply Earthworks SR-30 is just beautiful-sounding. Based on the David Blackmailer’s principle that just extending microphone’s frequency response outside normal range of just hearing will allow for much high definition sound, Earthworks SR-30 are just amazing for the overheads and also the acoustic instruments. A matched pair also runs around $1,800 in retail.