There are a lot of really nice stereo preamps out there that are absolutely in your price range. I think what you want to look for is probably a clean signal, good transient response, and the ability to add some grit if you want it. Another thing to look at in a preamp is a DI jack. That is, one with a jack specifically designed for taking a signal straight from a guitar or bass. A DI'd guitar through a good pre can sound so much better than the line out on your amp, especially when you want just a clean rhythm part. I think I mentioned it before, but I've heard good things about the Auteur from Black Lion Audio. I've heard it's a little noisy when you crank the gain all the way up, but you shouldn't need to do that on loud sources like drums and electric guitars.
http://www.blacklionaudio.com/Products/Black+Lion+Audio+Auteur+Preamp
It doesn't have a DI, but you can get one for about $100 from Radial:
http://www.sweetwater.com/store/detail/ProDI/
that sounds great, if you end up deciding you want that.
Another stereo preamp I've heard good things about is the RNP from FMR Audio:
http://www.fmraudio.com/RNP8380.htm
It does have two hi-z (DI) inputs, and is supposed to have a pretty nice clean sound.
One thing to consider would be going a little cheaper with your preamp - The M-Audio DMP3 and the ART MPA-II both seem to get pretty good reviews. Then, with the money you saved on the preamp, you could get a nicer couple of Mics. That 57 is gonna be essential, so go ahead and assume that cost. But if you look into some higher quality condensers, you'll be able to find some really nice ones in your price range. You can get a matched pair of small diaphragm condensers for anywhere from $200 to $500, and depending on the ones you get, they work great as drum overheads, or for stereo recording in general.
I really don't know enough about mics to make a definite suggestion here, but if you start looking around, shopping around for things in your price range, reading reviews (but not the ones on musiciansfriend and zzsounds or any of those other music megastore websites - I've usually found them to be less than reliable), you'll find something that looks like it'll work for you.
All that being said, the most important thing you can do to improve your sound is gonna be constantly reading and recording. Learn everything you can from reading online tutorials and books about recording, and at the same time, put it all into practice by doing it yourself. Try new things and use your ears to tell you what sounds good. In fact...
I'm gonna go ahead and capitalize this to make sure it's apparent that, despite everything I've said above, this is the most important thing I'm saying:
DON'T BUY A SINGLE THING UNTIL YOU ARE ABSOLUTELY SURE IT WILL IMPROVE YOUR SOUND. UNLESS YOU KNOW EVERY PIECE OF EQUIPMENT YOU ALREADY HAVE NOW BACKWARDS AND FORWARDS, INSIDE AND OUT, YOU WILL BE WASTING MONEY BY BUYING SOMETHING NEW. DON'T JUST BE SURE IT WILL IMPROVE YOUR SOUND, KNOW EXACTLY HOW IT WILL IMPROVE YOUR SOUND.
That $500 preamp is gonna look like a piece of crap if, after you get it, you realize that you could've been getting the sounds you wanted by having the amp and mic positioned in a slightly different way. The most important tools you have at your disposal are your ears and your brain. Practice practice practice, until you can justify your purchases completely, instead of just rationalizing them. I say this from experience. I still constantly have to stop myself from buying some new piece of equipment because it looks cool or probably does something I think I need. Until I'm sure that my current setup won't get me where I'm going, I leave the wallet in my pocket.
Jesus I'm long-winded.
One last thing:
before you buy any mics for drum recording (or with drum recording in mind), read up on mic positions and drum recording techniques. You can get a great sound with just a pair of mics - I just recorded a band and got great drum sounds in my living room with two mics. The more mics you add, the more control you have in the mixing phase over each individual drum. However, if you get the drums sounding great when you record them, then you don't need to do any more mixing. Plus, the more mics you have, the more you have to worry about introducing phase issues and ugly buildups of this or that kind of ambience. Just something to keep in mind.
