What I wonder about is whether any of the stuff is the same as you get sold in the UK but straight from the factory in a sense. I.e. cut out the middle man (retailer in the UK) and pay for the same item without the branding/UK support etc. I bought a few things from China like security cameras and then seen the same one for sale in the UK, often in places like Maplin's in the same box but with a change to the branding and instructions etc, customized to suit the retailer sending the item. I've bought a couple of gadgets from China/Hong Kong which were only about £20 but for sale at around 3 times the price in the UK.
Here's a good example:
http://www.maplin.co.uk/pan-tilt-wir...-camera-508703
I bought the identical item off ebay for around £30 (about £70 less):
http://www.ebay.co.uk/itm/VstarCam-I...item3a6ab69f14
The one off ebay works great although I know if it went wrong I face the hassle of returning to China if there is any kind of warranty in place for it.
One thing I do really think twice about is buying memory from abroad as I've heard about all the fake memory out there. I have a 1TB USB stick I bought really cheap as a fake and it's good fun for winding people up. Showed it to someone in my office and his response was quite loud and lots of heads turned!
I thought it might be worth taking a chance but then again it could be truly cheap and nasty...