Gosh, there are plenty of decent vocal mics in the $400 to $600 range. As you probably know, vocal mics are only half of the equation - the singer is the other half. Singers and mics will match up or they won't, even with very expensive mics.
Here's some thoughts on all arounders:
CAD VSM
ADK TC
SP T3
AKG 414 UBLS or TLII (used)
Some of the newer SE mics (haven't heard them, but getting good reviews)
There are many more.