There is currently a set of microphones being sold at Ebay. These are the old Sanyo HM-941 that came with the larger boxes like the Big Ben, 9994, 9998, 720, 820, and MX920. Ebay item#350844306380. I recently sold my Big ben and could have used a set these suckers. 

Hi Stereo mad, sorry for the late response, just got off work. I believe this is the link

http://www.ebay.com/itm/350844...id=p3984.m1555.l2649

If not just key in the item number under advanced search or by typing big ben microphone on the search bar. hope that helped.

wow these were next city from where i live.