the vendors will give you one price and then the price goes up the longer it takes you to decide whether or not to buy it or if you walk away the price goes up, if you come back for it the price has gone up due to the fact it now must be worth more since you come back for it. We didn't shop in the market areas that where inside a big warehouse type area it was way too dangerous for tourist. Stay clear of the inside vendors market, there's pickpocketers and just a shady bunch in that area. We went into this area for supplies a few times but it was wasn't a good feeling!
Don't carry a purse or alot of money
Buy off the street vendors they are safe and nice to deal with, more than once I held my hand out with change and they never took more than what the price was in the fruit market areas and fruit stands.