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Sorry I cant give you the answer you want but should you be going to Sousse medina anyway. The hassle from the shop keepers is very agressive they will not just let you look at their goods. Much cheaper than Tescos is one of their favourite lines.
The Medina in Tunis is about 20 minutes drive away. I think that the medina in Sousse would be too far away to visit when you only have 5 hours in port. The Medina in Tunis is well worth a visit thoug.