Thought I would add one more reference point to the NiceDiaper.com comments.
I ordered two pairs of (different) PUL pants from them back at the end of June. It's very hard to get a clear idea of what these would be like from their website, but given that they were both supposed to be highbacks and I haven't found highback PUL anywhere else, it seemed reasonable to give it a try. One was listed as medium which seemed to be the right size by the size chart. The other was "one-size" with velcro closure, which seemed less likely, but one never knows. They were quite cheap, 11 and 12 $US. Shipping was relatively high, 12$US but not unusual as a minimum for air freight.
I took about twice as long to get to the US than the site said it would and then it took a week and a half to clear customs. ("Hmmm", the agent said, "Better just check on why this guy wants adult plastic pants. Could be some strange sort of conspiracy." -)
They were both too small, and neither were highback. The one-size had a belt closure, but no leg closures. So they are a total loss to me, but it was still a worthwhile trial.
So my take-away:
There are big size differences between the US and Chinese markets, and these are not necessarily completely reflected in the measurements that are given. I haven't actually measured them and I never did their metric/inch conversion, so I don't know where the difference lies. So I would be very careful ordering anything that sizing really mattered on.
Shipping is likely to be quite slow and may be pretty expensive, but prices seem quite low.
They were declared as clothing and I very much doubt customs even shook them to see if they rattled. So I wouldn't worry about customs knowing about your strange tastes, but I would count on it taking awhile to make it's way through the pile.
I doubt that I would order again from them again, but I could see that someone who knew what they were undertaking could possibly be happy with them.