I have not seen anything readily available on the market that I would say is good.
However, if you have or know someone with a 3D printer, there are a number of very impressive designs on Thingiverse. Of course it would require a substantial amount of work to get it working, but those are about the best I have seen. In a small desktop size range, there isn't going to be anything I would consider really good as in high precision, accurate motion, repeatable motion, etc. These size robot arms run on small R/C servo motors which due to their intended purpose do not have very high resolution.