Why do you want to limit yourself to electrets if you want high quality? I mean, there are some very good ones and even a few that are arguably first-rate, but most are decidedly inferior to the better traditionally-polarized condensers (or to good RF condensers, for that matter).
Do you really need (for example) microphones that run on plug-in powering rather than phantom powering? Or microphones that draw very little current, so that you don't have to carry lots of batteries or change batteries frequently? Electrets don't necessarily offer either of those features, nor are those features necessarily best served by electrets.
I'm just trying to imagine why anyone would willingly adopt the constraint of the electret polarization principle in a search for high-performance microphones. It's a seemingly irrelevant and counterproductive constraint, is all.
--best regards