Worked in Tunisia for a tour operator for a few years. Whisky is like currency . Buy a couple to take with you (maybe in duty free). You will be able to haggle a leather jacket for a few dinars and a bottle of whisky.
I took Whiskey to trade and they were not interested at all!
Didn't like Tunisia at all felt quite insecure you are plagued to death by the locals, they watch and follow you like hawks when you are in there shops, they are too 'touchy feely' with men as well as women.
The souk beware they like to pretend they know you they ask the taxi driver which hotel you are from. The taxi's are death traps and they turn off there meters, it is very cheap to buy things
but be careful