Here's the one that I use for my web exclusive stuff:
http://yokattaweb.jp/
There's also this person too, who goes by OkinawamToySeller on HenshinJusticeUnlimited's boards:
http://hobbyjapan.ocnk.net/
I can tell you right now that they are pretty reliable, though Iv'e had closer contact with Yokatta.
So far, I haven't gotten hit with taxes ordering from Yokatta yet *Knocks on wood*. They usually under declare the value, and mark the parcel as gift or personal use.