The RE20 is a stone cold classic R&B vocal microphone.
BUT they normally run well over $200 new or used.
I think at e-bay you could score a new one under $400.
(if you find two under $200 I'll take one of them right now!)
The EV PL20 is the same microphone with a different paint job,
and they typically run slighty less $$ used because people mistakenly think they're RE20 "rejects".
If you've got the dough and are fine with it not being designed for hand held use, either should be a fine choice too.
The Electro-Voice EV 666 is the closest in sound to the RE20.
You'd have to pry mine from my cold dead fingers!
As a famous pro AE said, they sound like a RCA 77DX run through
a (high end) tube mic pre. Not better than the RE20, just a bit thicker with less detail.
Sometimes you can find them used for about $200 or so if you're lucky. Primo ones can go $300+ easy, as they're rare now.
Make sure you can get the funky cable that matchs it, and the original mic clip, if you find one.
The downside on the EV 666 is that if they go kaput, AFAIK there's no way to repair them as EV stopped doing that due to a parts shortage. Plus I have a second one where the internal EQ circuit failed, but it still works albeit thinner sounding.
Another great rival to those EV's is the Shure SM7, which again normally sells above $200 in good condition or better. It's a "go to" microphone for many pro studios.
The EV's are easier for the relatively inexperienced studio vocalist though (like me!) IMHO.
Chris