The Souk, Marrakech
Even with a native guide, be prepared to negotiate with the merchants within the souk, which is the open air market in Marrakech where traders have traded goods for over 1,000 years. The merchants are so persistent they will follow you throughout every store to sell you that hand crafted piece of art that will hold your wine bottle when you return home.
You'll find yourself, or as I did negotiating endlessly for sport. You will be consumed by the seller's charismatic charm, persistence & personality and you will laugh as you keep saying no to his counter offers, However, hold steady because you are negotiating in Dirham, the currency of the country and at the end you will finally get your price if your mate doesn't pull you away sooner out of exhaust. ...and when this is all over and you are back in your hotel room beating your chest in victory, look at what you bought. It is still that time tiny piece of tin craft you just overpaid.
I also advise you to be careful of the rug salesmen. They ship anywhere in the world.