There are basically two price points in LCDs right now: $200+/- for cheap 19" panels and $300+/- for good 19" panels. Note that you can get 6-bit or 8-bit color depth in both price points. After some searching it looks like 8-bit panels are roughly the same price as 6-bit panels for similar quality (similar quality meaning the quality of a specific 6-bit panel compared with other 6-bit panels falls at some point, and the point where each panel falls relative to other similar panels is the same, not the image quality. Confused?).
So really 6-bit v 8-bit is not about price, it's about preference.
Ultimately the things I recommend looking for are a DVI connection (this is critical IMO) and a name brand with good user ratings. Viewsonic is my favorite, but NEC, Samsung and Dell also make good quality panels with BenQ and LG making decent budget-priced panels.