not compatible...do you mean the plugs aren't the same? If that's the only problem many folks handy with a soldering iron could help you out by changing the connector (provided the mic is compatible in impedance and other specs).
what model is it?
as far as lavs go, have a look at http://www.kenstone.net/fcp_homepage/lavs_brockett.html
the more senior members of this forum can give you their take on various mics. I myself can't tell you much first hand (old and limited budget are laughably understated when describing my church's sound gear).
Hope that helps.