You can find lots of stuff in Jiddah. Even brand names are no problem at all. But I had to find out, that almost all brand articles are more expensive than back home in Austria. This goes for expensive watches, jewelery,...
The only cheap thing that I found, were 25 "Twix" bars at the duty-free-shop for about 5 $.
What to buy: Sweets
What to pay: Less than at home