icom vhf f521 dtmf

I'd like to use a DTMF microphone for phone patch and echolink on the local ham repeaters using my F521, but prices for the MH-133 and HM-118TN are much lower than the ICOM recommended HM-100TN (about $45 more). Are there other mics compatible with the F521, or do I really need the HM-100TN? Thanks.