Visualizers are just plain expensive. There's no way around it, and until then I will not be buying into it. I am using American DJ's myDMX for PC control, which comes with a (not the greatest) visualizer application. Even when I'm using the "real" console (Avolites Pearl) I'll still sometimes build my show in myDMX. You can download the software for free, or buy it for $300 and get a "free" dongle for PC control.
It helps get a general idea, but more beneficial for me is that it allows me to show my clients what their show will look like. The first time I printed and showed one client (my best, actually) the stage layout for a recent fashion show they acted like it was the most amazing thing they'd ever seen. It really goes a long way to be able to show a client at least a rough idea of what everything will look like once the lights come on, before you've even loaded the truck with any gear. I'm just not sure it's worth $5000 (at least to me at this point).