You can probably find some used ones of name brands on various sites, maybe even refurbished ones. But brand new, your looking at probably $800+ for a name brand unit, e.g. Pinoneer, Kenwood, Sony, Eclipse, etc..
Also keep in mind, allot of the units have the various abilities like BlueTooth, ipod interface, AV control, back up camera, etc.. but they usually will require additional modules which will up the price even more. In other words, your probably going to be looking at a $1000 for anything decent with the features your probably after.
That said, I have the Pioneer Avic-Z2 with the options shown in my sig. Absolutely awesome head unit.