I'm actually going through a similar delima. I'm tired of my 17'' CRT with 1280x1024 max. I want something bigger...a lot bigger. This weekend I almost spent $999.99 on a Sceptre 30'' LCD TV Monitor, until I looked at TV monitors at CompUSA today and decided they looked like crap as a monitor, and only have a 1280x768 resolution.
I switched my search over to just large LCDs. I found a great 20.1'' Sony that looks huge, and has a 1600x1200 resolution. CompUSA wanted $899 for it, but found it at newegg.com for only $710! I ordered it this afternoon. I'll let you know how it is when it arrives later this week.
I realize $710 is still a bit out of your prefered price range, but from what i've been able to find, it's about the best you'll be able to do for a LCD with that kind of resolution.
EDIT: Actually, check out newegg.com:
http://www.newegg.com/Product/Produc...9:9240&bop=and
Scroll down a bit. They have a 20'' Sceptre LCD with the high res for only $529. They have a bunch in the $600 range too