If you look around the net you'll find a few Chinese snake sites. They're mostly Hong Kong dealers that sell chinese snakes (here's another one for instance http://www.probreeder.com/images/collection/ema-350.jpg ). The have some very pretty pictures and they may even be able to send snakes out that look like what they advertize. I think you'll find that the wild caught snakes they sell are pretty uniformly very unlikely to survive. In addition you'll have to get an import license to bring them in. And finally comes the leap of faith of sending money to China and hoping the dealers honor their side of the bargain.
Another possibility is to work with some American importers who work with some of these very same exporters. They'll be taking the majority of the risk so you'll pay much more than if you buy direct. And once again the snakes are pretty poor survival bets.
A third way to get wild-caught mandarins is to buy them from a retailer who takes the trouble to cherry pick the best of the imports and nurses them back from the edge of the grave. These will be still more expensive but much more likely to survive.
You can also go for captive hatched eggs from wild caught females. This is even better but of course even more expensive.
And finally you can buy captive bred snakes which are practically fool-proof from the point of view of survival but of course most expensive.
So what's the advantage of wild-caughts? I guess the only advantage is the possibility of getting new morphs (like the anerythristics and striped and other pattern and color differences). But you'd better be prepared for blood sweat and tears. Because until Chinese breeders appear on the scene, the exports you'll find are going to be problematic at best.
Not trying to be a downer
John