I have been on Zillion and have an account set up.
Whilst it is a good alternative, the biggest problem is that it just isn't trademe.
It doesn't quite have the member numbers at the moment, although I am hoping that will change.
I still find trademe easier to navigate, and yes, the 5.5% success fee is kinda a pain in the ass, but I have somewhat countered that by selling lots of small goods at low prices. It takes you longer to accumulate a good profit, but it feels much better when TM is only taking a couple of dollars from your item.