I had two but, unfortunately, had to sell one due to a very tight financial times. The one I kept is still functional except, the two little metal balls at the base of the trackball cavity are worn flat from use. So, now the trackball wont move smoothly but, basically "shudders". Recently purchased tools may let me turn the little metal balls 180 degrees and get it working again.
150 pounds? that would work out to be around $300 each down here in Oz.