www.dealextreme.com
This website comes in handy when you need to buy devices and components where excessive quality isn't really something you need (like things that are hard to fuck up, cables and whatnot).
Almost everything on there is shit, but it's cheap shit, and when shit works it's pretty much the place to go. Also free shipping.
If you're going to be in china and want to pick up electronics anyway then your only bet is to know basic inner workings of the things you're buying. Know which things they're going to skimp on for price, and which things function well on low grade parts. For instance if you want an MP3 player, pick one out that doesn't have all of the perks like a color screen or fancy features, because the screen and the CPU are the first two things that are going to be cheesed in. If you're buying a cell phone or tablet go for an android device that has the latest OS on it because you're never going to see a service pack, make sure it has a capacitive touch screen with a good resolution, that the processor is suitable for what you're using it for and that the memory isn't fucking awful. Also they might lie about the specs in person, I don't know. Don't be an idiot.
Basically the easier it is to make, the better chance it's not going to fuck up.
The best things to pick up there are batteries. Be it for your existing devices, or external batteries that charge things off of USB. The expensive component on these is the actual battery, but they're easy to produce and the accompanying electronics are negligibly cheap. You can generally find a backup USB battery that retails in the states for like 70-150$ for about 15-30$ and functions identically. For internal device batteries you can generally pick up spare cell phone batteries for your specific device for 2-10$.