Its hard for me to know what you like so I'll stick to generalities with proven track records. The following list of things are good deals to be bought in Greece either because they grow here, are made here, or are imported here and sold in bulk vs tiny packages like 3$ herbs in the supermarkets in the US.
see my 'What not to pack' page for some more tips concerning clothing. Below follow some pictures of typical things for sale in touristy type locals. Here we are below in Tinos island Cyclades which is primarily a Greek destination. Many Greeks visit the very popular Church of the Virgin here.
Combined with your usual fare like jewelry and beach wear are local island produce. In this case we have sun dried tomatoes, capers and other local bounty like soaps and dried herbs. You will see this type of offering a lot in varying locations all over Greece.