Darn, had a whole writeup to post, but Krispy's advice is even better!
For what it's worth, I ended up getting a set of used AKG 391's as my first set of "open" mics, paid $350 used. I chose them because the sound quality is considered decent, the self noise specs are pretty good, the interchangeable capsules let you change the pickup pattern of the mics if you want, and it accepts a range of phantom power voltages (I think 9-52v?).
Of course, after a while I succumbed to the gear slut disease and got some AKG 460's, which I'll be sending to JW at some point fo rthe mod (should sound good with my MixPre / Shure FP24)....
Good luck!
Mike