Yo, I live in China now.
Lots of fakes in China, the gadget markets are huge and mostly filled with fake stuff. (but you may get an awesome deal if you spend some time in there.)
If he buys from a legit shop like bestbuy, suning (major electronic stores) then he's not nothing to worry about but then the price is quite a bit higher.
In terms of Xbox, never brought one before so I dunno
Tablets - many fakes, rather buy from a big store unless he knows his sh*t
Laptop - get from big stores else it might be refurbed
Coming back into SA, if the stuff he buys is for personal use then go through the green lane.
If theres loads of stuff, then rather be safe and pay some duties
I came back in October, dressed like a hobo, unshaven for a week, with an ipad 3, new pc for my bro, a new laptop all packed with an old dirty luggage case, through the greenlane; and not one person looked or questioned me.
Some do's:
If he buys from gadget market (not a big franchise), always ask for a discount...if he comes to beijing ask for a 90% discount (they usually increase the ask price by 100% for foreigners.)
If he thinks the price is right but they arent willing, walk away becoz they will call u back.
Test the things before paying, dont leave it out of sight (some dodge places shows u a working phone, then packs a dud.)
Asking for an invoice may increase cost (by 6%) but is useful if you caught at customs, otherwise customs might use the local market price to charge you duty, which may be substantially higher than what you paid. (not applicable for big stores, they always provide invoice even if you dont want it.)
Donts:
Dont cause any fights, if they blame you for breaking something, best to call the police.
Dont follow anyone into a corner
Dont lose ur passport
Dont believe in something that is too good to be true