Personally, I think a good monitor is always worth it. Most likely, you will have it for multiple major PC upgrades, and it is the only part of the PC you stare at for hours.
I have an AOC Spectrum 9Glrs at work and I can't stand it. Sure the screen is big, but it has the annoying curved screen, and bad glare, and bad colors. I would take my 17 inch Dell Trinitron (Sony) over this any day. I have had it since 1997. During college, it was being used probably 22 hours or more a day. It has been used heavily. The AOC's here at work always seem to be dying and don't have much chance in making it 3 yrs.
My 17 inch has a new scratch on it, and I am now in the market for a 19 inch as well. I have pretty much settled on the CPD-G410R from Sony. Mwave has it for $325+$40 shipping.
I have also heard good things about the Samsung 955DF, and I think it retails for around $300 so you could find it for $250 online probably.
AnAndTech Samsung 955DF Review