As an eBay seller myself, with 100% feedback and 627 feedback, I feel that online marketplaces are rather safe. And yes, finding a truly good deal will be hard, after all, why would a seller want to undercut a competitor by THAT much when they know they can profit by just a slight undercut?
That being said however, there are tons of deals online, and you CAN get lucky.. I've never used taobao.com, but have been aware of it's existence. Yahoo Auctions (Hong Kong) still exists, and I have seen some WICKED deals for graphic tablets there I wanted to purchase before - which was about 30% lower than what I had seen for that particular model on eBay.
My online experience has been good. I've only been scammed once - when digital cameras were in its infancy, I had purchased a vertically-oriented camera (don't remember which make it was), and got scammed about $500 USD at that time. Learned my lesson after that, and know the tricks of the trade now I suppose.
But it certainly is true.. We're rather close to China. If you are seriously committed to getting a deal done - heck, just go to China.. I'm sure any serious money you commit may actually warrant the little one day trip if it's not too far out that is.
We all hear the horror stories of buying online (just check out Alibaba boards) - but I mean, it comes with the territory I suppose.. You do get what you pay for.