Used monitor under$600 with good bass low levels

Planning on doing some experimenting with inexpensive monitors.
A monitor that is a two-way that can be biamped would be prefered.
Also a wide dispersion tweeter.
Mind as well let the cat out of the bag, I will be mimicking the bolzano villetrie torres:

http://www.bolzanovilletri.com/products/series/campanile/torre/
Thanks in advance.