You might want to try wire spark erosion, thats how we got our jaws and leavers cut a few years back. It was around £500, but was 12mm thick, so yours might be cheaper. The place that did ours was NC Laser Cutting Services Ltd, Rochdale (http://www.andertongroup.comhttp://www.andertongroup.com or direct tel 01706 631277). Though they might have another cheaper way of doing it as they do alot of different stuff, no harm in asking.