Dell's 24" 2408WFP can usually be found either new on eBay or refurbished through the Dell outlet for < $400. It's got a great VA panel, I have two at work and bought my own for home. It also has a million different inputs (HDMI, DisplayPort, etc.) and support for SDHC, which the predecessor (2407WFP) did not.
Let me also just advise you to stay far, far away from any TN panel at any cost. I figured I'd just get the 22" UltraSharp at first, had to send it back because it's just not good enough for writing code.
Second on the TN type panels. Buy a panel type, not a manufacturer. Some shoddy ones like "AOC" or even Visio may use different (whatevers cheaper) panels over time and sell them as the same model number. I've got 2 AOC's I bought about 6 months apart. Both exactly the same model, one is great, one terrible.