There are several threads just like this on this forum if you poke around a bit, full of pics and folks' opinions on who they like best as far as after-market clip providers.
I myself have tried them all and have been an extremely faithful customer of Casey Lynch's for very good reason - he makes the best, most high quality ones out there. The eBay makers do make nice clips for other patterns that Casey's don't fit, but I'm not too enthused about the one maker on there that blatantly copies Casey's style of clip (Casey's came first) and makes a crappier version of it at that. Casey is an outstanding person to deal with, and a very generous gentleman, and he makes some very nice other Ti products (PM2 and Delica scales and prybars). If you Google "Spyderco Lynch clip", you'll see many examples (quite a few are my pics from here) and his BladeForums thread have many more. Cheers, Radioactive