Three in that range that are pretty exceptional -

True P-Solo

Grace Design's Model 101

And if you need a dual channel unit, FMR's RNP.

Any of which will set you back around $500 - Any of which can hang with some fairly impressive input chains.

what about somethin with tube?

I'll 2nd the Grace. Very good and clean pre.
Love the RNP also, I like everthing that I've ever used from FMR. Real bang for a buck stuff,JMHO.

For real cheap I like the Studio Projects VTB-1. I got one free and use it with my cheap Oktava ML-53 Ribbon Mic.
Together they produce a very unique colour.

Want'in something with a tube for under 500 bones,
Check out the Brick. Groove Tubes Brick. About as good as it gets for uder 500 bones.

Peace...........Scoobie

At $189 per channel, 2 tubes per channel, the Electro Harmonix 12AY7 tube mic pre is an amazing little pre. It has fantastic focus with cardioid mics and very nice dimension with omni capsules. An incredible bang for the buck.