Purchases should be paid only in national currency as any other currencies will not be accepted by merchants. The currency can be exchanged in local banks or private currency exchange offices meanwhile using individual services is banned by law.
Setting off to the market one should have enough change as high-denomination note may be a trigger to put up a price for a merchant and a buyer thus is challenged not to get the rest.
One of the worst challenges of Marrakesh is pickpockets that is why one should be extremely watchful and keep track of personal things. One should not keep documents and substantial sums of cash by oneself without urgent need. Plenty of jewelry and gems on will as well attract the pickpockets.
The best time for shopping is weekdays as weekends features extreme skyrocketing of the prices. Markets and private shops welcome bargaining that will help sufficiently reduce the price.
The next sufficient problem of Marrakesh is beggars who are aimed exactly at foreign tourists. One should avoid talking to them or giving them some cash otherwise the beggars will follow the tourist all day long.