Shoestring Astronomy GPUSB guiding adapter for mounts/guide cameras/guiding programs needing USB support from laptop. See
http://shoestringastronomy.com for details*. Hardly used. US$75 from U.S., my price AUD50 plus postage or pickup Sydney.
*"The GPUSB guide port interface adapter plugs directly into a USB port on your computer or a USB hub attached to your computer. Using an RJ-12 cable, the adapter connects to the guide port of your telescope mount. This guide port interface uses optocouplers to electrically isolate the computer from the telescope, eliminating a possible source of electrical interference. This interface adapter requires no external power source since it receives its power via the USB cable."