There was a full rear kit on ebay last month for a gu4. It went to only one bidder and it sold for $850 brand spanking new in the box from a Nissan dealer in Victoria clearing out old stock. Pays to check out ebay every week!
Hey skiman, it is a very good system, thats why we got a ST-L, but I wouldnt have bothered if we had bought a ST, we planned it well and only looked at ST-L 's, for the kids and the dog and also to help keep the fridge cooler. If you do it let us know , you would be a very determined man. goodluck