There is no such thing as "good gamut". There is normal gamut and wide gamut. Are you referring to "good" color accuracy? Since you are only willing to spend $350 - $400 per monitor, the only thing I can recommend is the Dell U2311H or the NEC EA231WMi.
The Dell U2311H has decent enough color accuracy out of the box for something that simply rolls off the production line. But using a colorimeter will get you the best results.
Planning to use or purchase a colorimeter?
Yes == NEC EA231WMi
No == Dell U2311H