I dont know of any ready-made VR systems but you can put one together yoursef for less than $1400
Grab a set of these:
http://www.i-glassesstore.com/ig-svgapro.html
And one of these:
http://www.edimensional.com/products/trackir2.htm
You can use the head tracker with a normal monitor but then you have to train yourself to keep your eyes looking at the monitor while you move your head in the direction that you really want to look. With the headset, you dont have to worry about that.