The dynamic contrast is only a technical trick. The controller-board lowers or raises the brightness of the backlight depending on what is shown on the display. If you have a very dark scene, the brightness is turned down so you will get a nice black level and not a shiny dark-grey.
If you have a bright scene it operates in the other direction.
This trick only works good if you have moving pictures and the picture has more dark or bright parts. The dynamic contrast does not work well on a balanced picture.
Sometimes the dynamic contrast also affects some other settings to tweak the colors. That can look good, but it also can turn the shown picture into a teletubbie land 
There is also the risk that regions of the picture may show artifacts.
It is almost impossible to compare the dynamic contrast to a static contrast. Most TFT monitors with a TN panel have a contrast ratio (static) around 700:1.
If you want a monitor with a really good contrast you should put you hands on TFTs with a VA or IPS Panel.
300cd/m² is enough but there is another important thing: you should be able to decrease the brightness to a low level so it will not burn your eyes in a darker room.
It seems that you don't care much about gaming. Maybe the BenQ FP91GP could be interesting for you. I don't know how much it costs in your country but in Germany you can get it for 215 Euro.
This monitor has a VA panel and will offer you nice colors with a very good contrast and much better viewing angles than a TFT with a TN panel.
Of course you can also play games with this monitor but the moving blur might be a bit higher than on TN monitors.
Another good monitor with a little bit more comfort is the FSC P19-2 (non-P). In Germany it is available for 300 Euro.
