Here is my van. http://www.mp3car.com/vbulletin/work...cargo-van.html
I would suggest a head unit like the one I'm using since your new to car audio and want to stay on the cheap side. A tip is to stay away from cheap stuff like dual, pyle, pyramid and whatever other cheap brands there are. Saving money now on a head unit will cost you later when you have to tear the dash all apart again and replace it. Jvc and alpine both make good headunits.
Also if you are planning on putting in a touchscreen or a monitor close to the driver, using the computer to drive your amps is best. I dont have a carputer installed yet, this is why my van has a head unit.
The benefit of a headunit is that they normally have a cheasy 20watts rmsx4 amp to power speakers. This could save you from buying amps right now.