OP, you would want to be very careful buying a "used" fork off ebay, but that can be a very cost-effective way to go about it. There are lots of forks floating around the lightly used market due to them being cut too short by mistake. Many have never been ridden, just made too small for the original owners in the cutting process. Their loss can be your gain. Just do your best to verify that the fork was never crashed or damaged any other way. There are usually lots of Ritcheys to be had that way. Also be sure the steerer matches your frame in terms of dimensions, taper, etc.