I used to use three at once but then summer hit and I discovered that CRTs put out a lot of heat...
In my opinion the best place to shop is
NewEgg. Their prices are generally good, they carry pretty much anything you need, and have good service.
LCDs are still an area where, for the most part, you get what you pay for. A cheap display is not gonna have near the quality of a better (and therefore more expensive) one. There's too many ways to cut corners on LCDs (uneven backlights, cheap panels that have poor color reproduction and dead pixels, poor electronics) that let the bargain manufacturers put out something on the cheap, but really show in terms of how the finished product works.
Personally, I'm quite enamored with NEC's flat-panels, but a lot of people swear by Dells, and still others will recommend Samsung. Stay away from the off-brand stuff, or you'll likely end up regretting it.
Generally speaking, for a gaming display your going to want:
At least a 12ms response time. Any more and you will start to notice smearing when things are moving quickly on the display.
A full 8-bit color depth. Some panels have a 6-bit depth, which makes getting response times down simpler and makes things cheaper, but means that you will notice dithering when you've got things set at 32-bit color depth and something onscreen falls outside the monitor's gamut.
A DVI hookup, if your video card has one. Otherwise the digital output of your video card is getting converted to analog, and then back to digital again, which leads to degradation of image quality.
Contrast and Brightness... well, these are kinda subjective, in truth. I was darn near blinded by my LCD when I got it (NEC MultiSync LCD1770GX, if you're wondering) and I still only run it with the backlight at 65 percent or so. Contrast on LCDs is typically exaggerated compared to a CRT unless adjusted. I think the best way is probably to go into a brick and mortar store and look at a screen to see what it's like.
In fact, the best advice overall would be to go to the store and play around with a variety of displays until you get a feel for what combination of features and specs you prefer and then try and find where you can get that for the best price from a good manufacturer.