I’m in the same boat.
I am looking for a new shotgun for our second camera that only does 5 – 6 weddings a year, as the Senhieser MKE 300 now on it is subject to a lot of mobile phone interference, and I don’t want to buy another M6 for so little work.
My research has lead me to Asden SGM 1000, which the Australian distributor has tested against mobile phones for me, and he is sending out for me to test next week.
I notice it sells for US$350, and has very good specs, so maybe is worth testing for yourself.
Have also tested a Rode NT 2, but with very poor results in wind and input level distortion when standing next to the P.A. at several wedding receptions (Yes it WAS the microphone that was distorting, not the camera overloading. I was watching and riding the camera input level all night, but had very distorted audio anyway.)
Cheers Vaughan